Ok- the number 12 was just a thought, because it's a common quantity for frames on a roll. Maybe we do it in rolling groups of four - the first four to sign up are a group, the next four, group two, and so on.
As I said, I'm flexible on the film format. While I can enlarge anything from 4x5 on down, I didn't want to exclude folks who don't have big darkrooms with big enlargers from participating, but I figure that most folks on APUG have enlargers that at least will handle 2 1/4. I also didn't want to make people go out and buy negative carriers for something they don't otherwise use.
Here's a new thought - Post your film size preference(s) along with your name, and I'll match up groups of folks who use similar negatives. We'll stick to the four per group. How does that sound?