I've always wanted to try designing a 3D printed slinky, and what could be slinkier than a snake? It can stretch out to a full meter in length. It prints standing on end, using tree supports that form a cradle for the tail to keep it stable.

Post Printing

DO NOT just try to yank this apart after printing - the coils are easy to kink. First, remove the tree support base - it should break free pretty easily, but you can use cutters if necessary to help break it away. 

Then, to free up the spring, gently poke a thin blade, like a pocket knife or xacto knife into the gap between the coils and then then work the blade along the entire length of the coil to free it up. I actually used the back side of an xacto knife blade rather than the sharp edge, wiggling it a little as I went to break the coils free.