CNC'ing this would be the biggest waste... I can hook you up with somewhere that will prolly make them for somewhat of a reasonable price (definately better than the operating costs of a CNC) depending on the amount ordered. I mean what is your estimated cost so far?
Nice. REally size doesn't matter, and a regulator wouldn't be the best path. Get a OPRV from mcmaster 25-35 psi are fine. I've NEVER had complaints with them even by a man who protests a lot of blasters.