This is a bobble-head Skull toy with action bobbling brain. This toy use a 3D printed spring that supports the brain and makes it bobble.

No supports are required and you can use minimal infill (10% is fine). The brain bobbles best if you print that part with more infill to add weight, but it isn't necessary.

This was made from a couple of different things. First is the excellent "Human Skull Pot" model by LaLeahTortilla (https://www.printables.com/model/115570-human-skull-pot-with-drainage-hole/files).

The spring mechanism is based on the excellent bobble head collection designed by 3d-printy (https://www.printables.com/model/224836-emoji-printer-bobbleheads). Be sure to see his extensive collection of bobble-heads and other items.

Bobble-Head Assembly Tips:
The square spring hole in the skull is a little oversized to aid assembly. Note: For correct orientation, the spring needs to be installed with the flat side of the spring facing forward because the brain only fits on the spring one way. Install the spring into the skull first (crazy glue is recommended). The tool to install the spring is included here and its use is optional, but handy. Finally install the brain onto the spring. It also has an oversized hole and so glue is also recommended.

See the complete collection of my 3D print creations on Printables.com at:
https://www.printables.com/social/258622-rreibel/models

Enjoy!