This is a design by the brilliant Gael Langevin. I've often visited his stand at Maker Faires in Rome and continued to be amazed by his work. I already created this long ago (on an Ultimaker Original, remember the wooden box?), but have never shared any makes of it.
Also check out his Thingiverse collection: https://www.thingiverse.com/gael_langevin/designs
I only added the design of a servo gear that better fit my purposes.
The user re-uploaded this model. The user is not the original author of the model.