I have made my own throttles also, but not for an MB, and they weren't pretty! I can't help but wonder why you wanted to make four throttles? They have no function with the turbo and plenum which is done with runners and a throttle body on a plenum? Also, if you please what diameter is the throttle shaft, and what kind of fastenings are used to mount the throttle blades? For the person discussing throttle bodies; yes the 3.8L Gm unit is an execellent choice; complete with t.p.s. my last one cost 5dollars at the junkies. The head/runner flange can be made out of mild steel plate even in your garage with a hand drill. the basic technique is white paint on the head and press on the strap to pick up a pair of bolt locations; followed by two studs to match your strap with the two holes; more paint, more holes; more paint; big holes, etc. Exhaust tubing for the runners, 6" truck exhaust tube for the plenum; and bob's your uncle. Steel is a better material here than aluminum beause it conducts heat about 3.5 times more poorly.