  Physical input devices serve as a tactile interface between users and
computing systems. These devices are often complex assemblies that consist of
both electrical and mechanical components making customization difficult and
out of reach for non-engineers. While these components can now be 3D printed on
demand, they must still be independently designed and assembled. We present
FlexKeys, an approach in which devices that include both electrical and
deformable components can be created in a single print on a multi-material 3D
printer, requiring no assembly. Designers can customize devices including the
input type, travel distance and layout of keys, textures of surfaces, and route
all electrical signals directly to a microcontroller socket. In many instances,
these devices require no support material, producing a functional device the
moment a print finishes. We demonstrate this approach by creating a customized
keyboard and report on validation measurements of individual input keys as well
as highlighting additional designs. This work provides the first step towards
lowering the barrier to entry for non-engineers to design custom tactile
inputs, enabling occupational and physical therapists, clinicians, and
educators to design and create devices directly based on their assessments of
individual user needs.

Human-Computer Interaction