Cutting and gluing all those valley hinges and gussets is a pain and leaves lots of possible sources of leakage. I combine the valley hinges and gussets for each fold into one piece. A piece of leather 500mm long and 50mm wide, skived at each side and ends is glued into the circumference of the valley of each fold .One piece has replaced 6 valley hinges , 6 gussets and a lot of frustration. Do all the folds this way ,apply top runs then end runs and that's it. For a 6 fold bellows I count 92 separate pieces as being replaced by only 22.Would like to hear comments ,criticisms etc.