I have made an 8" x 20" camera. I saw the measurements for the 8 x 20 film holder and made the holder. Then I made the camera around that holder. Now I am in the process of making the bellows. Obviously there is a mathematical formula for the width of the stiffeners. I have visited the DIY Bellows page, and his formula is for a square bellows, which will not work. So I need help. The backstand is 21 1/2" x 10 3/4". The front stand is 7 1/2 square. The length of the bellows is 30". Will appreciate it if someone can help me. Thank you very much. Cliff

Cliff