To answer a couple questions, as of right now anything is possible for porting, length, ID etc. As for accuracy, it can be as accurate as your willing to pay for, I'm thinking +/- .002 will suffice, but could get it within ten thousandths of an inch if people are willing to pay more which I doubt. He actually normally does real firearm work so they are well set up for boring and honing barrels. I think pricing will be about $60 for a black bull barrel, just a strait OD without any porting if there interest on doing a small run. Is it safe to say most people would prefer a 0.675 bore? Bull barrels will be the cheapest/easiest to do for sure, I'll look into the extra cost to get them ported with a fancier look but it seems like basic bull barrels would be more popular.
I race toy cars, and you though paintball was expensive... Rcjunky's feedback