I'm starting my 5th bellows for my 8x10 project, and one of the problems I've run into in the past is getting a good bond between the cardboard (poster board) stiffeners and the fabric layers. So far I tried Loctite spray adhesive, rubber cement, and Scotch Super 77 spray adhesive. None of these provides good adhesion, and the fabric balloons out on me when folding the bellows. What are some glues you've used and had good luck with?