These clips keep your pegboard hooks securely fastened to the pegboard, instead of coming off along with whatever you were trying to take off the hook.

M clip.STL is designed to hold down a single pegboard hook. M clip double.STL is meant to hold down two hooks side by side. They are both designed to fit pegboard that is 3/16" thick with ¼" holes 1" on center. 

I printed these with a .4mm nozzle, .3mm layer height, and 4 perimeters.

In addition to the STLs, I have also included STEP files of each clip, as well as a 3mf of a full MK3S tray with 64 clips. If you want to modify the native CAD file, you can use OnShape Free and modify the files at these links: M clip or M clip double