Hi Bry,
Well I have looked at the tool and spoken to the Omega man, He and now I agree that what your plan is a bit unnecessary. Making the piece from Aluminium is pointless as it should never come in contact with the watch back as the pins are too long for that to happen. Making the pins from a material strong enough to withstand the torque means that a polished steel is much better than risking the pins bending, by using Brass, which would result in the back of the watch being damaged.
Having said all that, as an exercise in precision hole drilling I can make one and send it to you for a contribution to your favourite charity (that's not the local pub). I think a better option would be for you to buy some 2mm silver steel and replace your pins yourself which I think you are quite capable of doing. Another source of quality steel pins would be needle rollers from a bearing supplier, you would though have to flatten the rounded ends of the rollers as the holes in the watch back are not deep enough.
Ned
Edit; OOPS this should have been a PM