I've only use mild steel and welded on pieces of cut file for the jaws. I don't know if it will work but time will tell. The plans look OK but after looking at the Metal Man one I bought, the jaw plans lack a little detail. Having said that though, good old google should be able to fill in the blanks with that. If you just search google images until you find a picture like the CAD one at the top of this thread you should find them. They are also on 'scribd' if you subscribe to it. All free.

I'll add some more pics soon.