Z threaded rod anti-rattle bushing for MakerFarm Prusa i3

I got tired of hearing the threaded Z rod vibrating against the wooden hole it passes through at the top, so I printed some bushings to slip over the rods that snap into the holes.

It should fit loosely over the rod (providing no resistance), and has some small bumps on the bottom that make it a tight fit to push through the hole, but is loose once it pressed all the way through.