One of reasons I'm glad I have a lathe
I was putting together some storage shelves, and I thought it would be nice to attach some pegboard to the shelving unit.
The legs on the shelving unit had keyhole shaped holes for holding the shelf brackets in place. I was hoping to be able to do something like this:
The square part of a 1/4” carriage bolt looked like it would fit perfectly in the narrow part of the keyhole, but the head was too large. So I chucked up the bolt in my lathe and turned the diameter of the head down. I used a couple of nuts with slits (cut via hacksaw) so I could chuck up the bolt.
Worked like a charm.