In v3 I included holes for guiding drill bits.
I used it to build 12mm plywood drawers and a 15mm plywood cabinet. I printed 6 and was barely enough, next build I'll print 2 more.
They fit snugly and can be hard to remove after a glue-up, but simply hitting them with a board will detach them.
Works well in PLA.
The author hasn't provided the model origin yet.