I finished a drawing today. It's just a way to get a STEN bolt without milling; all you need is a bench lathe, welding and files. Since I don't live in a democracy, I uploaded the file for download at:
www.angelfire.com/rebellion/weapons/gunthers_sten_gun_files.htm
This idea can be great (if perfected) for caliber modifications or lighter bolts for subsonic ammo.