I am building an 8x10 field camera or two for myself, a son and a friend. Next year I hope to tackle an 8x20. I'll start this next project if I get the right sort of answers to the following questions. What kind of prices are being charged for these film holder type beasties? Are there any exceptional technical challenges to be overcome if I decide to make a film holder? If I figure out how to build a holder and do a good job with it, would there be much of a market for new holders I might produce?