We present a fabrication system called AirForce that allows users to create large-scale, load-bearing animated structures from a single inflatable tube. AirForce builds on the personal fabrication of animated truss structures, based on which it replaces not only the static elements with tube, but also introduces tube-based actuators that integrate with that same tube. This ‘single-tube’ design affords efficient single-person assembly, excellent power-to-weight ratio, easy transport and setup, and 100% material reuse. We show three variants of actuators: buckling actuators for pushing, muscle actuators for pulling, and telescoping actuators for large forces. Our blender plugin enables users to place actuators in structures and export instructions for efficient fabrication. We demonstrate a 6DOF motion platform that lifts humans and an 8m high animatronic T-rex that animates with 3DOF, enabled by custom hardware components. In our technical evaluation, the three actuators delivered 480N, 1420N, and 2330N peak forces, respectively.

We demonstrate AirTied [Rambold et al., 2023], a device that fabricates truss structures in a fully automatic fashion. AirTied achieves this by unrolling a 20cm-wide inflatable plastic tube and tying nodes into it. AirTied creates nodes by holding onto a segment of tube, stacking additional tube segments on top of it, tying them up, and releasing the result. The resulting structures are material-efficient and light as well as sturdy, as we demonstrate by creating a 6m-tower. Unlike the prior art, AirTied requires no scaffolding and no building blocks, bringing automated truss construction into the reach of personal fabrication.

We present AirTied, a device that fabricates truss structures in a fully automatic fashion. AirTied achieves this by unrolling a 20cm-wide inflatable plastic tube and tying nodes into it. AirTied creates nodes by holding onto a segment of tube, stacking additional tube segments on top of it, tying them up, and releasing the result. The resulting structures are material-efficient and light as well as sturdy, as we demonstrate by creating a 6m-tower. Unlike the prior art, AirTied requires no scaffolding and no building blocks, bringing automated truss construction into the reach of personal fabrication.

In this demonstration, we show a selection of twelve past CHI and UIST projects by our lab, which taken together aim at helping the field of digital fabrication using laser cutters transition past makers—and towards true non-experts, which we refer to as “consumers”. Our software systems provide such non-experts with domain knowledge (Kyub and fastForce), hardware and machine knowledge (Constructable, LaserOrigami, LaserStacker, springFit, kerf-canceling mechanisms, Assembler3 and autoAssembler), assembling laser-cut objects (FoolProofJoint, Roadkill, HingeCore) and demonstrate our contributions in solving these challenges over the course of twelve projects during the last few years.

We present Kerfmeter, a hardware + software device that automatically determines how much material the laser cutter burns off, also known as kerf. Its knowledge about kerf allows Kerfmeter to make the joints of laser cut 3D models fit together with just the right tension, i.e., loose enough to allow for comfortable assembly, yet tight enough to hold parts together without glue—all this without user interaction. Kerfmeter attaches to the head of a laser cutter and works as follows: when users send a model to the laser cutter, Kerfmeter intercepts the job, injects a brief calibration routine that determines kerf, dilates the cutting plan according to this kerf, and then proceeds to fabricate the cutting plan. During the calibration routine, Kerfmeter cuts a 2cm Archimedean spiral and uses a motor to rotate it in place until it jams against the surrounding material; the angle at which the spiral jams allows Kerfmeter to infer kerf. The calibration process takes about 20s, which is >10x faster than traditional, manual kerf calibration, while also eliminating the need for expertise. In our technical evaluation, Kerfmeter produced functioning press fit joints reliably at a precision comparable to traditional manual kerf strips. Kerfmeter makes it easy to sample repeatedly; we demonstrate how this allows boosting precision past any traditional kerf strip.

We demonstrate fastForce, a software tool that detects structural flaws in laser cut 3D models and fixes them by introducing additional plates into the model, thereby making models up to 52x stronger. By focusing on a specific type of structural issue, i.e., poorly connected sub-structures in closed box structures, fastForce achieves real-time performance. This allows fastForce to fix structural issues continuously in the background, while users stay focused on editing their models and without ever becoming aware of any structural issues. In our study, six of seven participants inadvertently introduced severe structural flaws into the guitar stands they designed. Similarly, we found 286 of 402 relevant models in the kyub [1] model library to contain such flaws. We integrated fastForce into a 3D editor for lasercutting (kyub) and found that even with high plate counts fastForce achieves real-time performance.

Building large structures from small elements, creating life-size animated creatures, or making contraptions that we can ride on have almost certainly been everyone's childhood dreams. However, researchers and practitioners of personal fabrication have been mainly focusing on creating objects that fit into a human palm, also called "hand-size" objects. The reason behind this is not only because of the size limitation of consumer-grade fabrication machinery but also because of the very long printing time and high material costs of large-scale prototypes. To overcome these limitations, I combine 3D printed hubs and ready-made objects, such as plastic bottles, as well as welding steel rods into a certain type of node-link structures called "trusses". However, the actual challenge behind my work is not only about achieving the size, but ensuring that the resulting large structures withstand the orders of magnitude larger forces than their hand-sized counterparts. Designing such structures requires substantial engineering know-how that users of personal fabrication equipment, such as makers, typically do not possess. By providing the lacking engineering know-how, my three end-to-end software systems TrussFab, TrussFormer, and Trusscillator enable non-experts to build such human-scale static, kinetic, and human-powered dynamic devices, such as pavilions, large-scale animatronic devices, and playground equipment. These systems achieve this by allowing users to focus on high-level design aspects, such as shape, animation, or riding experience, while abstracting away the underlying technicalities of forces, inertia, eigenfrequencies, etc. To help building the designs, the software generates the connector pieces and assembly instructions. With this body of work, I aim at democratizing engineering that enables individuals to design and fabricate large-scale objects and mechanisms that involve human-scale forces.

We present fastForce, a software tool that detects structural flaws in laser cut 3D models and fixes them by introducing additional plates into the model, thereby making models up to 52x stronger. By focusing on a specific type of structural issue, i.e., poorly connected sub-structures in closed box structures, fastForce achieves real-time performance (106x faster than finite element analysis, in the specific case of the wheelbarrow from Figure 1). This allows fastForce to fix structural issues continuously in the background, while users stay focused on editing their models and without ever becoming aware of any structural issues. In our study, six of seven participants inadvertently introduced severe structural flaws into the guitar stands they designed. Similarly, we found 286 of 402 relevant models in the kyub [1] model library to contain such flaws. We integrated fastForce into a 3D editor for lasercutting (kyub) and found that even with high plate counts fastForce achieves real-time performance.

Trusscillator is an end-to-end system that allows non-engineers to create human-scale human-powered devices that perform oscillatory movements, such as playground equipment, workout devices, and interactive kinetic installations. While recent research has been focusing on generating mechanisms that produce specific movement-path, without considering the required energy for the motion (kinematic approach), Trusscillator supports users in designing mechanisms that recycle energy in the system in the form of oscillating mechanisms (dynamic approach), specifically with the help of coil-springs. The presented system features a novel set of tools tailored for designing the dynamic experience of the motion. These tools allow designers to focus on user experience-specific aspects, such as motion range, tempo, and effort while abstracting away the underlying technicalities of eigenfrequencies, spring constants, and energy. Since the forces involved in the resulting devices can be high, Trusscillator helps users to fabricate from steel by picking out appropriate steal springs, generating part lists, and producing stencils and welding jigs that help weld with precision. To validate our system, we designed, built, and tested a series of unique playground equipment featuring 2-4 degrees of movement.

Current Virtual Reality (VR) technologies focus on rendering visuospatial effects, and thus are inaccessible for blind or low vision users. We examine the use of a novel white cane controller that enables navigation without vision of large virtual environments with complex architecture, such as winding paths and occluding walls and doors. The cane controller employs a lightweight three-axis brake mechanism to provide large-scale shape of virtual objects. The multiple degrees-of-freedom enables users to adapt the controller to their preferred techniques and grip. In addition, surface textures are rendered with a voice coil actuator based on contact vibrations; and spatialized audio is determined based on the progression of sound through the geometry around the user. We design a scavenger hunt game that demonstrates how our device enables blind users to navigate a complex virtual environment. Seven out of eight users were able to successfully navigate the virtual room (6x6m) to locate targets while avoiding collisions. We conclude with design consideration on creating immersive non-visual VR experiences based on user preferences for cane techniques, and cane material properties.

We present PIVOT, a wrist-worn haptic device that renders virtual objects into the user's hand on demand. Its simple design comprises a single actuated joint that pivots a haptic handle into and out of the user's hand, rendering the haptic sensations of grasping, catching, or throwing an object anywhere in space. Unlike existing hand-held haptic devices and haptic gloves, PIVOT leaves the user's palm free when not in use, allowing users to make unencumbered use of their hand. PIVOT also enables rendering forces acting on the held virtual objects, such as gravity, inertia, or air-drag, by actively driving its motor while the user is firmly holding the handle. When wearing a PIVOT device on both hands, they can add haptic feedback to bimanual interaction, such as lifting larger objects. In our user study, participants (n=12) evaluated the realism of grabbing and releasing objects of different shape and size with mean score 5.19 on a scale from 1 to 7, rated the ability to catch and throw balls in different directions with different velocities (mean=5.5), and verified the ability to render the comparative weight of held objects with 87% accuracy for ~100g increments.

We present an interactive editing system for laser cutting called kyub. Kyub allows users to create models efficiently in 3D, which it then unfolds into the 2D plates laser cutters expect. Unlike earlier systems, such as FlatFitFab, kyub affords construction based on closed box structures, which allows users to turn very thin material, such as 4mm plywood, into objects capable of withstanding large forces, such as chairs users can actually sit on. To afford such sturdy construction, every kyub project begins with a simple finger-joint "boxel"-a structure we found to be capable of withstanding over 500kg of load. Users then extend their model by attaching additional boxels. Boxels merge automatically, resulting in larger, yet equally strong structures. While the concept of stacking boxels allows kyub to offer the strong affordance and ease of use of a voxel-based editor, boxels are not confined to a grid and readily combine with kuyb's various geometry deformation tools. In our technical evaluation, objects built with kyub withstood hundreds of kilograms of loads. In our user study, non-engineers rated the learnability of kyub 6.1/7.

Several systems have illustrated the concept of interactive fabrication, i.e. rather than working through a digital editor, users make edits directly on the physical workpiece. However, so far the interaction has been limited to turn-taking, i.e., users first perform a command and then the system responds with physical feedback. In this paper, we present a first step towards interactive fabrication that changes the workpiece continuously while the user is manipulating it.

We present an interactive editing system for laser cutting called kyub. Kyub allows users to create models efficiently in 3D, which it then unfolds into the 2D plates laser cutters expect. Unlike earlier systems, such as FlatFitFab, kyub affords construction based on closed box structures, which allows users to turn very thin material, such as 4mm plywood, into objects capable of withstanding large forces, such as chairs users can actually sit on. To afford such sturdy construction, every kyub project begins with a simple finger-joint "boxel"-a structure we found to be capable of withstanding over 500kg of load. Users then extend their model by attaching additional boxels. Boxels merge automatically, resulting in larger, yet equally strong structures. While the concept of stacking boxels allows kyub to offer the strong affordance and ease of use of a voxel-based editor, boxels are not confined to a grid and readily combine with kuyb's various geometry deformation tools. In our technical evaluation, objects built with kyub withstood hundreds of kilograms of loads. We demonstrate the kyub software to the CHI audience and allow them to experience the resulting models first hand.

We present TrussFormer, an integrated end-to-end system that allows users to 3D print large-scale kinetic structures, i.e., structures that involve motion and deal with dynamic forces. TrussFormer builds on TrussFab, from which it inherits the ability to create static large-scale truss structures from 3D printed connectors and PET bottles. TrussFormer adds movement to these structures by placing linear actuators into them: either manually, wrapped in reusable components called assets, or by demonstrating the intended movement. TrussFormer verifies that the resulting structure is mechanically sound and will withstand the dynamic forces resulting from the motion. To fabricate the design, TrussFormer generates the underlying hinge system that can be printed on standard desktop 3D printers. We demonstrate TrussFormer with several example objects, including a 6 legged walking robot and a 4m tall animatronics dinosaur with 5 degrees of freedom.

Several systems have illustrated the concept of interactive fabrication, i.e. rather than working through a digital editor, users make edits directly on the physical workpiece. However, so far the interaction has been limited to turn-taking, i.e., users first perform a command and then the system responds with physical feedback. In this paper, we present a first step towards interactive fabrication that changes the workpiece continuously while the user is manipulating it. To achieve this, our system FormFab does not add or subtract material but instead reshapes it (formative fabrication). A heat gun attached to a robotic arm warms up a thermoplastic sheet until it becomes compliant; users then control a pneumatic system that applies either pressure or vacuum thereby pushing the material outwards or pulling it inwards. Since FormFab reshapes the workpiece continuously while users are moving their hands, users can interactively explore different sizes of a shape with a single interaction.

We present metamaterial textures---3D printed surface geometries that can perform a controlled transition between two or more textures. Metamaterial textures are integrated into 3D printed objects and allow designing how the object interacts with the environment and the user's tactile sense. Inspired by foldable paper sheets ("origami") and surface wrinkling, our 3D printed metamaterial textures consist of a grid of cells that fold when compressed by an external global force. Unlike origami, however, metamaterial textures offer full control over the transformation, such as in between states and sequence of actuation. This allows for integrating multiple textures and makes them useful, e.g., for exploring parameters in the rapid prototyping of textures. Metamaterial textures are also robust enough to allow the resulting objects to be grasped, pushed, or stood on. This allows us to make objects, such as a shoe sole that transforms from flat to treaded, a textured door handle that provides tactile feedback to visually impaired users, and a configurable bicycle grip. We present an editor assists users in creating metamaterial textures interactively by arranging cells, applying forces, and previewing their deformation.

Several systems have illustrated the concept of interactive fabrication, i.e. rather than working through a digital editor, users make edits directly on the physical workpiece. However, so far the interaction has been limited to turn-taking, i.e., users first perform a command and then the system responds with physical feedback. In this paper, we present a first step towards interactive fabrication that changes the workpiece while the user is manipulating it. To achieve this, our system FormFab does not add or subtract material but instead reshapes it (formative fabrication). A heat gun attached to a robotic arm warms up a thermoplastic sheet until it becomes compliant; users then control a pneumatic system that applies either pressure or vacuum thereby pushing the material outwards or pulling it inwards. Since FormFab reshapes the workpiece while users are moving their hands, users can interactively explore different sizes of a shape with a single interaction. Author Keywords: personal fabrication; interactive fabrication; direct manipulation; 3D modeling tools. ACM Classification Keywords: H5.2 [Information interfaces and presentation]: User Interfaces. INTRODUCTION Recently, Willis et al. [28] proposed the concept of Interactive Fabrication. The key idea is to bring the principles of direct manipulation [20] to the editing of physical objects: Instead of working on a digital 3D model and producing the physical version only at the end, users make edits directly on the physical workpiece and see it change immediately. Figure 1: (a) FormFab changes the workpiece while the user is interacting with it. First, a heat-gun warms up the workpiece. Once the material has become compliant, (b) the user’s hand gesture interactively controls a pneumatic system that applies pressure or vacuum, pushing the material outwards or pulling it inwards. Early interactive fabrication systems, such as Shaper [28], CopyCAD [5], and constructable [14], allow for hands-on editing on the physical workpiece. However, their interaction is best described as turn-taking: users first provide input to the system and then the system responds with physical feedback. Since there are two discrete steps, users can only explore one option per turn [2]. In this paper, we propose an interactive fabrication system that can change a workpiece’s shape while the user is interacting. This enables users to explore different sizes of a shape with a single interaction rather than in multiple turns. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, toing with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Permissions@acm.org.

 TEI '19, March 17–20, 2019, Tempe, AZ, USA 
 © 2019 Association for Computing Machinery.
 ACM ISBN 978-1-4503-6196-5/19/03...$15.00 https://doi.org/10.1145/3294109.3295620 We accomplish this using a process called formative fabrication, which rather than adding or subtracting, reshapes the existing material. In our system, users interactively control a pneumatic air pump that applies either pressure or vacuum to a compliant thermoplastic sheet, thereby pushing the material outwards or pulling it inwards (Figure 1b). RELATED WORK Our work builds on existing work in exploring new interaction models for 3D modeling and personal fabrication. Spatial Modeling with Virtual Feedback In a first attempt to facilitate interaction, researchers proposed to let users create models as if they were manipulating an (invisible) physical workpiece: In SpatialSketch [27] users define the shape of a lamp by describing its surface using their hands. Similarly, in Virtual Pottery [7] users shape virtual clay by moving the hands as if they were physically shaping clay. Dress-up [26] added physical tools: Using the ‘surface’ tool, users sketch the shape of dresses directly on a physical mannequin, the ‘cut’ tool then removes surfaces. Similarly, Tool-Device [1] uses a knife tool to cut objects and a hammer to join them. Extending this approach, researchers developed systems that provide visual feedback directly in the environment: In Situated Modeling [11], users sketch objects in the context they belong to; an AR headset allows users to visually evaluate editing steps in place. MixFab [25] follows the same approach, but uses a beam splitter and a display to overlay physical and virtual content. Interactive Fabrication based on turn-taking The first set of interactive fabrication tools were based on turn-taking: In Shaper [28], users first touch a screen and only after finishing their input, the machine extrudes a drop of foam onto the build plate. In CopyCAD [5], users first draw with a pen onto a piece of wood, and then a mill creates the corresponding geometry. Similarly, in Interlacing [4], users first lay down a pattern of sticks, which the robot then copies, and in Gestural Form [8] users first draw a line onto the ground and afterwards the robot constructs a brick wall on it. In Constructable [14], users first draw with a laser pointer onto the workpiece inside a laser cutter and then the drawing is cut by the laser. Similarly, in ReForm [24] users first draw onto the clay and then a clay extruder adds or a mill removes geometry. Towards Interactive Fabrication Beyond Turn-Taking One group of systems that point towards interactive fabrication beyond turn-taking are smart handheld tools that enable users to physically replicate digital models. Haptic Intelligentsia [12], for instance, only extrudes when the user is following a predefined path. Similarly, PositionCorrecting Router [18] and Enchanted Scissors [31] only route and cut when the user is on the path, and Augmented Airbrush [22] only sprays when the user holds it at the correct location. Extensions to this line of work, such as the FreeD [33, 34] and D-Coil [17] also allow users to modify the shape of the model. Closest to our work is a system called RoMA [16] that enables user and fabrication device to work concurrently. However, since it uses additive and subtractive fabrication, it does not allow to quickly explore different shapes in the design process. Formative fabrication Formative fabrication is a process that can quickly reshape sheets into different profiles. It has been widely used in architecture, for instance, to create building facades [9]. Within HCI, it has been used to make 3D objects from 2D sheets either using the heat from a laser cutter (LaserOrigami [13]) or a microwave (MOR4R [32]). Other researchers used formative fabrication to quickly create objects on demand and recycle them by reversing their shape (Dishmaker [3]). Formative fabrication has also been explored in the context of post-customization (HotFlex [6]), custom textures for 3D shapes (Computational Thermoforming [21]), fast replication of shapes (ProtoMold [30]) and traditional turn-taking interactive fabrication (DrawForming [29]). However, none of these systems supports changing the workpiece’s shape while the user is providing input. FORMFAB FormFab is an interactive fabrication system based on formative fabrication that allows users to explore different sizes of a shape while interacting (Figure 1b). First, users draw an outline of the area they want to reshape using their index finger (Figure 2a). When the user removes the finger, the path is beautified by our software. The robotic arm then warms up the area using a heat gun (Figure 2b). Figure 2: (a,b) Drawing outline and heating. (c,d) One interaction, i.e., the same part is first pulled out and then pushed in. After the material has reached its compliance point, the robotic arm moves out of the way. The user can then perform a pinch gesture, which activates the pneumatic system. If the user’s hand moves away from the workpiece, the pneumatic system increases the air pressure and the compliant area inflates (Figure 2c). If the user’s hand moves back towards the workpiece, the pneumatic system reduces the pressure and the compliant area deflates (Figure 2d). While step 1 of the user interaction, i.e., drawing the outline, still follows the turn-taking interaction model, step 2, i.e., defining the extrusion amount provides physical feedback while the user is interacting. Walkthrough: Making the sculpture of a teddy head Figure 3 shows the steps to make the sculpture of a teddy bear’s head using our system. We first draw a circle onto the flat workpiece and after the robot has heated up the area, we reshape the sheet to explore different dimensions for the head—making it larger and smaller within seconds until we find the right shape (Figure 1b). Using the same interaction steps, we add the ears to the head of the teddy (Figure 3a/b): As can be seen in the accompanying video, we reshape the right ear for about 30s to find the best shape, and then add the left ear accordingly. We now add the snout: to explore the best size, we repeatedly scale the snout by moving our hand to different distances from the workpiece. We then add a tip on top of it. In the last step, we create the eyes (Figure 3c). This time, we move our hand towards the workpiece, thereby applying vacuum that extrudes the eyes inwards. Figure 3: Making the teddy bear head: (a,b) drawing and extruding the left ear, (c) extruding an eye. Figure 4 shows the final teddy head made from a 30x30cm sheet (thickness: 4mm). Making the teddy head took only 9 minutes including the time for exploring different sizes for various parts of the design and also includes the time for heating and for letting t

We present a new haptic device that enables blind users to continuously track the absolute position of moving objects in spatial virtual environments, as is the case in sports or shooter games. Users interact with DualPanto by operating the me handle with one hand and by holding on to the it handle with the other hand. Each handle is connected to a pantograph haptic input/output device. The key feature is that the two handles are spatially registered with respect to each other. When guiding their avatar through a virtual world using the me handle, spatial registration enables users to track moving objects by having the device guide the output hand. This allows blind players of a 1-on-1 soccer game to race for the ball or evade an opponent; it allows blind players of a shooter game to aim at an opponent and dodge shots. In our user study, blind participants reported very high enjoyment when using the device to play (6.5/7).