A sphere in a sphere. I designed this on my own, but it appears to be analogous to (and not as nice as) https://www.thingiverse.com/thing:2204181 https://www.thingiverse.com/thing:2006177 -- really, use those instead.

OpenSCAD source included for educational purposes.

While labeled as a work-in-progress, I'm pretty unlikely to return to it.

Printrbot

Play

No

No

Be careful if resizing (units are in millimeters): supports are built-in, and making the model smaller will prevent them from providing support. Making the model bigger may cause the supports to be too strong.

Expect bits of filament to fall out while fidgeting.

Designed in OpenSCAD.