Doodads for securing belts

I made these little deals out of delrin to lock my belts. I put 30 lbs on the belt with a fish scale and they didn’t budge. I think I am still going to use heat shrink just to make it look clean.

I used .25" delrin and had to rub them on sandpaper just a bit to get them to fit into the slot. I used a 1/16" bit 30 ipm, .03 doc