SustainaPrint: Making the Most of Eco-Friendly FilamentsWe present SustainaPrint, a system for integrating eco-friendly filaments into 3D printing without compromising structural integrity. While biodegradable and recycled 3D printing filaments offer environmental benefits, there is a trade-off in using them as they may suffer from degraded or unpredictable mechanical properties, which can limit their use in load-bearing applications. SustainaPrint addresses this by strategically assigning eco-friendly and standard filaments to different regions of a multi-material print—reinforcing the areas that are most likely to break with stronger material while maximizing the use of sustainable filament elsewhere. As eco-friendly filaments often do not come with technical datasheets, we also introduce a low-cost, at-home mechanical testing toolkit that enables users to evaluate filament strength before deciding if they want to use that filament in our pipeline. We validate SustainaPrint through real-world fabrication and mechanical testing, demonstrating its effectiveness across a range of functional 3D printing tasks.2025MPMaxine Perroni-Scharf et al.Desktop 3D Printing & Personal FabricationCustomizable & Personalized ObjectsSustainable HCIUIST
Mallet-Based Assembly: Enabling Load-Bearing Laser-Cut ModelsLaser cutting has a long tradition of building load-bearing 3D objects based on box joints and T-joints, as these joints are naturally robust against compression and shearing. Achieving robustness against tension, however, is challenging. One presumed solution is to make all joints extremely tight, to the point where they can only be assembled using a mallet. However, our survey found that making joints tight can cause models to break during assembly. In this paper, we identify the 10 underlying issues and present techniques for overcoming them: by extending parts with what we call scaffolding or by adjusting the models’ assembly order, so as to bypass states that are subject to these issues. Based on our user study and analysis of laser-cut models, scaffolding speeds up assembly for an average of 14% of the assembly operations per model, which in turn gives an average of 1.3x speed-up per model, and 70% of the models would benefit from the adjusted assembly order, that in the absence of such, would require higher assembly effort.2025SKShohei Katakura et al.Laser Cutting & Digital FabricationUIST
All in One: Rapid Game Prototyping in a Single ViewCreating games involves frequent prototyping to quickly obtain feedback. In this paper, we explore the impact of removing a traditional game engine’s separation of scene and game logic that supports scalability to large projects and, instead, combine scene and game logic in a single view. In our tool, Pronto, designers connect game objects with visual representations of behavior to define game logic in the scene view, thus exposing any concern of the prototype to the designer within one click. To explore the implications of the trade-off between scalability and speed of access, we conducted a cognitive walkthrough and an explorative user study comparing prototyping in the Godot game engine and in Pronto. Godot’s separate views made it appear more structured and reliable to users, while Pronto’s scattered game logic accelerated editing and gave users the impression of progressing faster in their implementation.2025EKEva Krebs et al.Hasso Plattner Institute, University of PotsdamGamification DesignPrototyping & User TestingCHI
MµSE: Supporting Exploration of Software-Hardware Interactions Through ExamplesProgrammers regularly explore the execution of code examples to verify assumptions by adding print statements or commenting in and out setup code in their implementation to isolate code paths of interest. In our formative study on developing embedded programs, where proximity to hardware dictates low abstraction levels, we observed that wrong assumptions occur frequently. However, traditional editors for embedded programs lack support for such explorations. Consequently, programmers have to re-create and clean up setup and print statements in their code for each example. MµSE supports isolated explorations of code examples by promoting examples to first-class entities that allow for the mocking of side effects from code and hardware, which could interfere with examples, and automatically showing values of expressions, replacing print statements for debugging. Our exploratory study found that MµSE supports participants in developing an understanding of software and hardware components and identifying false assumptions from observation of incorrect behavior.2024PMPaul Methfessel et al.Hasso-Plattner-InstituteImmersion & Presence ResearchCircuit Making & Hardware PrototypingCHI
AirTied: Automatic Personal Fabrication of Truss StructuresWe present AirTied, a device that fabricates truss structures in a fully automatic fashion. AirTied achieves this by un-rolling 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.2023LRLukas Rambold et al.Desktop 3D Printing & Personal FabricationLaser Cutting & Digital FabricationShape-Changing Materials & 4D PrintingUIST
Structured Editing for All: Deriving Usable Structured Editors From GrammarsStructured editing can show benefits in learnability, tool building, and editing efficiency in programming. However, creating a usable structured editor is laborious and demanding, typically requiring tool builders to manually create or adjust editing interactions. We present Sandblocks, a system that allows users to automatically generate structured editors for every language with a formal grammar available. Our system's \emph{input reconciliation process} acts on arbitrary syntax trees to provides consistent interactions across our generated editors. Our editors' editing experience is designed to be familiar to users from textual editing but, compared to previous work, requires no manual annotation in the grammars. We demonstrate our editors' usability across languages through a user study (N=18). Compared to conventional text editors, even with minimal training, participants only took on average 21% (JS), 34% (Clojure), and 95% (RegExp) longer and reported that editing felt natural with a score of 6/7.2023TBTom Beckmann et al.Hasso Plattner Institute, University of PotsdamProgramming Education & Computational ThinkingKnowledge Worker Tools & WorkflowsCHI
Kerfmeter: Automatic Kerf Calibration for Laser Cutting 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.2023SKShohei Katakura et al.Hasso Plattner Institute, Hasso Plattner InstituteLaser Cutting & Digital FabricationCircuit Making & Hardware PrototypingCHI
Relatedly: Scaffolding Literature Reviews with Existing Related Work SectionsScholars who want to research a scientific topic must take time to read, extract meaning, and identify connections across many papers. As scientific literature grows, this becomes increasingly challenging. Meanwhile, authors summarize prior research in papers’ related work sections, though this is scoped to support a single paper. A formative study found that while reading multiple related work paragraphs helps overview a topic, it is hard to navigate overlapping and diverging references and research foci. In this work, we design a system, Relatedly, that scaffolds exploring and reading multiple related work paragraphs on a topic, with features including dynamic re-ranking and highlighting to spotlight unexplored dissimilar information, auto-generated descriptive paragraph headings, and low-lighting of redundant information. From a within-subjects user study (n=15), we found that scholars generate more coherent, insightful, and comprehensive topic outlines using Relatedly compared to a baseline paper list.2023SPSrishti Palani et al.University of California, Allen Institute for AIExplainable AI (XAI)Prototyping & User TestingCHI
FlowAR: How Different Augmented Reality Visualizations of Online Fitness Videos Support Flow for At-Home Yoga ExercisesOnline fitness video tutorials are an increasingly popular way to stay fit at home without a personal trainer. However, to keep the screen playing the video in view, users typically disrupt their balance and break the motion flow --- two main pillars for the correct execution of yoga poses. While past research partially addressed this problem, these approaches supported only a limited view of the instructor and simple movements. To enable the fluid execution of complex full-body yoga exercises, we propose FlowAR, an augmented reality system for home workouts that shows training video tutorials as always-present virtual static and dynamic overlays around the user. We tested different overlay layouts in a study with 16 participants, using motion capture equipment for baseline performance. Then, we iterated the prototype and tested it in a furnished lab simulating home settings with 12 users. Our results highlight the advantages of different visualizations and the system's general applicability.2023HJHye-Young Jo et al.KAISTAR Navigation & Context AwarenessFitness Tracking & Physical Activity MonitoringCHI
HingeCore: Laser-Cut Foamcore for Fast AssemblyWe present HingeCore, a novel type of laser-cut 3D structure made from sandwich materials, such as foamcore. The key design element behind HingeCore is what we call a finger hinge, which we produce by laser-cutting foamcore “half-way”. The primary benefit of finger hinges is that they allow for very fast assembly, as they allow models to be assembled by folding and because folded hinges stay put at the intended angle, based on the friction between fingers alone, which eliminates the need for glue or tabs. Finger hinges are also highly robust, with some 5mm foamcore models withstanding 62kg. We present HingeCoreMaker, a stand-alone software tool that automatically converts 3D models to HingeCore layouts, as well as an integration into a 3D modeling tool for laser cutting (Kyub [7]). We have used Hinge-CoreMaker to fabricate design objects, including speakers, lamps, and a life-size bust, as well as structural objects, such as functional furniture. In our user study, participants assembled HingeCore layouts 2.9x faster than layouts generated using the state-of-the-art for plate-based assembly (Roadkill [1]).2022MAMuhammad Abdullah et al.Shape-Changing Interfaces & Soft Robotic MaterialsLaser Cutting & Digital FabricationUIST
FoolProofJoint: Reducing Assembly Errors of Laser Cut 3D Models by Means of Custom Joint Patterns We present FoolProofJoint, a software tool that simplifies the assembly of laser-cut 3D models and reduces the risk of erroneous assembly. FoolProofJoint achieves this by modifying finger joint patterns. Wherever possible, FoolProofJoint makes similar looking pieces fully interchangeable, thereby speeding up the user’s visual search for a matching piece. When that is not possible, FoolProofJoint gives finger joints a unique pattern of individual finger placements so as to fit only with the correct piece, thereby preventing erroneous assembly. In our benchmark set of 217 laser-cut 3D models downloaded from kyub.com, FoolProofJoint made groups of similar looking pieces fully interchangeable for 65% of all groups of similar pieces; FoolProofJoint fully prevented assembly mistakes for 97% of all models.2022KPKeunwoo Park et al.Hasso Plattner InstituteLaser Cutting & Digital FabricationCHI
Trusscillator: a System for Fabricating Human-Scale Human-Powered Oscillating DevicesTrusscillator 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 by 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.2021RKRobert Kovacs et al.Desktop 3D Printing & Personal FabricationShape-Changing Materials & 4D PrintingUIST
AutoAssembler: Automatic Reconstruction of Laser-Cut 3D Models Recent research showed how to import laser cut 3D models encoded in the form of 2D cutting plans into a 3D editor (assembler^3), which allows users to perform parametric manipulations on such models. In contrast to assembler^3 , which requires users to perform this process manually, we present autoAssembler, which performs this process automatically. AutoAssembler uses a beam search algorithm to search possible ways of assembling plates. It uses joints on these plates to combine them into assembly candidates. It thereby preferably pursues candidates (1) that have no intersecting plates, (2) that fit into a small bounding box, (3) that use plates whose joints fit together well, (4) that do not add many unpaired joints, (5) that make use of constraints posed by other plates, and (6) that conform to symmetry axes of the plates. This works for models that have at least one edge joint (finger or t-joint). In our technical evaluation, we imported 66 models using autoAssembler. AutoAssembler assembled 79% of those models fully automatically; another 18% of models required on average 2.7 clicks of post-processing, for an overall success rate of 97%.2021TRThijs Roumen et al.Laser Cutting & Digital FabricationShape-Changing Materials & 4D PrintingUIST
Roadkill: Nesting Laser-Cut Objects for Fast AssemblyWe present Roadkill, a software tool that converts 3D models to 2D cutting plans for laser cutting—such that the resulting layouts allow for fast assembly. Roadkill achieves this by putting all relevant information into the cutting plan: (1) Thumbnails indicate which area of the model a set of parts belongs to. (2) Parts with exposed finger joints are easy to access, thereby suggesting to start assembly here. (3) Openings in the sheet act as jigs, affording assembly within the sheet. (4) Users continue assembly by inserting what has already been assembled into parts that are immediately adjacent or are pointed to by arrows. Roadkill maximizes the number of joints rendered in immediate adjacency by breaking down models into “subassemblies.” Within a subassembly, Roadkill holds the parts together using break-away tabs. (5) Users complete subassemblies according to their labels 1, 2, 3…, following 1 > 1 links to insert subassemblies into other subassemblies, until all parts come together. In our user study, Roadkill allowed participants to assemble layouts 2.4 times faster than layouts generated by a traditional pair-wise labeling of plates.2021MAMuhammad Abdullah et al.Laser Cutting & Digital FabricationCircuit Making & Hardware PrototypingUIST
FastForce: Real-Time Reinforcement of Laser-Cut StructuresWe 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 (10^6x 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.2021MAMuhammad Abdullah et al.Hasso Plattner InstituteLaser Cutting & Digital FabricationCircuit Making & Hardware PrototypingCHI
Assembler^3: 3D Reconstruction of Laser-cut ModelsWe present assembler^3 a software tool that allows users to perform 3D parametric manipulations on 2D laser cutting plans. Assembler^3 achieves this by semi-automatically converting 2D laser cutting plans to 3D, where users modify their models using available 3D tools (kyub), before converting them back to 2D. In our user study, this workflow allowed users to modify models 10x faster than using the traditional approach of editing 2D cutting plans directly. Assembler^3 converts models to 3D in 5 steps: (1) plate detection, (2) joint detection, (3) material thickness detection, (4) joint matching based on hashed joint "signatures", and (5) interactive reconstruction. In our technical evaluation, assembler^3 was able to reconstruct 100 of 105 models. Once 3D-reconstructed, we expect users to store and share their models in 3D, which can simplify collaboration and thereby empower the laser cutting community to create models of higher complexity.2021TRThijs Jan Roumen et al.Hasso Plattner InstituteLaser Cutting & Digital FabricationCircuit Making & Hardware PrototypingCHI
Haptic PIVOT: On-Demand Handhelds in VRWe 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.2020RKRobert Kovacs et al.Force Feedback & Pseudo-Haptic WeightHaptic WearablesUIST
Kerf-Canceling Mechanisms: Making Laser-Cut Mechanisms Operate across Different Laser CuttersGetting laser-cut mechanisms, such as those in microscopes, robots, vehicles, etc., to work, requires all their components to be dimensioned precisely. This precision, however, tends to be lost when fabricating on a different laser cutter, as it is likely to remove more or less material (aka “kerf”). We address this with what we call kerf-canceling mechanisms. Kerf-canceling mechanisms replace laser-cut bearings, sliders, gear pairs, etc. Unlike their traditional counterparts, however, they keep working when manufactured on a different laser cutter and/or with different kerf. Kerf-canceling mechanisms achieve this by adding an additional wedge element per mechanism. We have created a software tool KerfCanceler that locates traditional mechanisms in cutting plans and replaces them with their kerf-canceling counterparts. We evaluated our tool by converting 17 models found online to kerf-invariant models; we evaluated kerf-canceling bearings by testing with kerf values ranging from 0mm and 0.5mm and find that they perform reliably independent of this kerf.2020TRThijs Jan Roumen et al.Laser Cutting & Digital FabricationUIST
Virtual Reality Without Vision: A Haptic and Auditory White Cane to Navigate Complex Virtual WorldsCurrent 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.2020ASAlexa F. Siu et al.Stanford UniversitySocial & Collaborative VRVisual Impairment Technologies (Screen Readers, Tactile Graphics, Braille)CHI
Detecting Visuo-Haptic Mismatches in Virtual Reality using the Prediction Error Negativity of Event-Related Brain PotentialsDesigning immersion is the key challenge in virtual reality; this challenge has driven advancements in displays, rendering and recently, haptics. To increase our sense of physical immersion, for instance, vibrotactile gloves render the sense of touching, while electrical muscle stimulation (EMS) renders forces. Unfortunately, the established metric to assess the effectiveness of haptic devices relies on the user's subjective interpretation of unspecific, yet standardized, questions.<br>Here, we explore a new approach to detect a conflict in visuo-haptic integration (e.g., inadequate haptic feedback based on poorly configured collision detection) using electroencephalography (EEG). We propose analyzing event-related potentials (ERPs) during interaction with virtual objects. In our study, participants touched virtual objects in three conditions and received either no haptic feedback, vibration, or vibration and EMS feedback. To provoke a brain response in unrealistic VR interaction, we also presented the feedback prematurely in 25% of the trials.<br>We found that the early negativity component of the ERP (so called prediction error) was more pronounced in the mismatch trials, indicating we successfully detected haptic conflicts using our technique. Our results are a first step towards using ERPs to automatically detect visuo-haptic mismatches in VR, such as those that can cause a loss of the user's immersion.2019LGLukas Gehrke et al.Technical University of BerlinBrain-Computer Interface (BCI) & NeurofeedbackCHI