Summary

I made this cougar mascot bobblehead in our school colors. The model uses a compression spring and the dimensions are configured to fit the spring. The spring I used was from Uxcell (5.5 x 0.5 x 42mm/0.22" x 0.02" x 1.6"(ODWire DiaL)), purchased through Amazon.com at $7.48 for a pack of 20. So you may need to adjust for a different spring.

The spring was hot glued into the head, then fit over the peg and hot glued to the body. It bobbles very nicely.

This figure is a mash up using the body from http://www.thingiverse.com/thing:1220886, the paws and tail from http://www.thingiverse.com/thing:182323, and the head from a finger puppet model that's not on Thingiverse.

https://youtu.be/HvzdJh3KLYs