Two prinable spring options included! This is a derivative (or remix rather) of my 3D scanned fox decor, which is here on Thingiverse: http://www.thingiverse.com/thing:166984 Read instructions before printing. The original model was uploaded to Tinkercad and the final assembly as well as the spring were modeled from there. Check out the awesome bobbling action! http://youtu.be/nvFR8FkpMzg Update: I went through a few different revisions of springs. Here is what I learned: Any spring printed in PLA will slowly sag over time. Therefore I added spring v0. This should support, with the aid of some hot-glue, any <8mm spring. You can find these at most hardware stores including Harbor Freight, and Amazon. Read instructions for proper lengths. The springs are keyed and should not be printed in PLA or any other easily fatigued plastic. It is designed to be loose fitting and hot-glued into place for easy manipulation should it ever kink or break. "spring v0" requires a <8mm spring to be glued within each of the pockets of each end-piece. The overall length of this assembly should be between 32mm and 35mm from end to end. You can cut or stretch your spring to accommodate this. Split the "head body" plate into its two parts if your printer's build area is too small.