This is a replica of the popular Bongo Tie rubber band fastener for holding things together, just add a rubber band! These are also great for attaching a cable to a pole or two long or bulky objects together.
It's a few millimeters shorter than the original but this makes it more stable to print and fits better with normal sized rubber bands. I may add a different sizes in the future.
I printed these in ABS at .2 layer height with 2 shells and 50% hex fill.
I got it to print with no raft on my heated bed with Kapton but it seems to be easier to use a raft so they don't fall over.