  This paper presents FoamFactor, a novel material with tunable stiffness and
compressibility between hydration states, and a tailored pipeline to design and
fabricate artifacts consisting of it. This technique compounds hydrogel with
open-cell foams via additive manufacturing to produce a water-responsive
composite material. Enabled by the large volumetric changes of hydrogel
dispersions, the material is soft and compressible when dehydrated and becomes
stiffer and rather incompressible when hydrated. Leveraging this material
property transition, we explore its design space in various aspects pertaining
to the transition of hydration states, including multi-functional shoes,
amphibious cars, mechanical transmission systems, and self-deploying robotic
grippers.
