I printed off a few of these for my workshop.

They can be printed quickly at 0.3mm with no supports.

The bottom of the cleat will protrude back to give additional support on the wall. There should also be a gap where you can push a peg to lock it to the wall.

I've got them happily holding up custom plane, file, and other tool holders so far.

Inspired from Start Making (Woodworking)'s video on French Cleats (https://www.youtube.com/watch?v=Fx0RANQ59vs)