Material suggestions?

[Highpower]

Greg, I can't say it's never been done before, but I've never heard of anyone trying that. It sounds like a recipe for disaster to me though, trying to cut only on one edge of the broach. Any bit of side load on a broach will snap them in half like a dried twig. Too expensive for me to experiment with I'm afraid.   

I will most likely finish up the sides with the method that Darren talked about. I've done the same type of thing using the quill on my mill to square up inside corners with very good results. My poor man's manual shaper.