Would this interest anyone?

[Splint]

If you're serious about getting them cast dont do any machining until you've fully discussed your part and the casting technique with the engineer at the foundry. The patterns may need to be made slightly larger than the finished componant to allow for shrinkage as the casting cools after pouring (somewhere about 2% for aluminium but the foundry would be your best source of information on that) and machining or buffing the casting also needs to be considered as varying techniques of casting will have differing surface finishes. Speak to the guys at the foundry before you do anything.
Cheers
Splint

[cadcam]

if wants a decent finish then I would say a wax investment tool would be made.
Follow splint on that there is a Shrink factor for investment casting.