Hoptimist

A fully 3D printable version of a Hoptimist! Print yourself a bouncy companion for your desk! It'll happily sit there bopping away for a few seconds after a little tap on the head.

The springiness is achieved using a horizontal coil spring instead of a vertical helical spring, which means it can be printed easily. 

Printing:

I'd recommend printing in PETG (or other filaments with minimal creep over time), as the spring will gradually lose its bounce due to the weight of the head if printed in PLA.

Support is needed for the underneath of the body, and for the nose. It isn't needed anywhere else.

Any layer height under 0.2mm will work fine, but I don't see why 0.3mm shouldn't work.