I finished this up a couple of weeks ago, but still haven’t found time to take some decent photos. I posted some drawings of this earlier and have yet to finish updating them but I’ll get to that.
Anyway, picture below, lookit.
I tested it on some copper pipe and it seems to work really well. The only problem is that the rollers could use a little bit of a chamfer so they don’t score the pipe. I’ll fix that up next time I use it. Anyway, the design seems to work nicely. It’s a lot more effort than buying one for $150, but an interesting project in any case.