The catch: it's a home for a hermit crab.
Yes, 3D printing has produced pre-fab replacement homes for "needy hermit crabs". It's actually not a laughing matter, as hermit crabs habitually reside in leftover shells from other creatures, discarding and replacing them as the crab grows in size. The problem these days is that there aren't a lot of new shells being produced as many species are having issues in a time of climate change.
Enter Elizabeth Demaray, who began the "Hands Up" project to "meet the needs of natural life forms". She selected the hermit crabs, as they are undergoing a severe housing shortage. The design has an excellent space to weight ratio, making it entirely suitable for our little crabby friends.
Designed using rapid prototyping techniques, the bio-degradable plastic will outlast the crab, but not degrade the environment.