I know that trying to mill with a drill press is a big no-no, but I did some light work with my press and a Harbor Freight X-Y vice. I first cut opposing flat faces into the outside of my footpeg spacers, and then turned the cylinder and clamped it between the flats and put an 8° slant on the inside surface, which matches the outward bend I put in the inner plates. I definitely had some chatter, but I managed to complete the task with no apparent harm to my work pieces or my drill press.
I decided to give them a little stress test. And, yeah, they’re plenty strong enough.
