I think many alt-process printers would like a frame at least 4 inches greater in each dimension than the negative. I like to have nice, larger borders on my pt/pd/gum prints. But, I've got all the frames I need, so I won't be part of your market. The best frame I own is a Great Basin 16"x24". Beautifully crafted with great springs. If I was making new frames, I would model them after this.