"To fold the canvas" means to carefully bend and crease a piece of fabric or material used for painting or artistic purposes, so it can be stored or transported with ease. Full definition
A heated foot pad and folding canvas chair are also included, so you have everything you need to get your sauna time! (geekwrapped.com)
All R129s came standard with an aluminum detachable hardtop that was fitted by folding the canvas roof down and manually attaching the hardtop. (en.m.wikipedia.org)
Instead of the Ford's folding canvas top, the Lincoln Mark X had a retractible roof, which seemingly every manufacturer was trying to build in the early 2000s. (bestride.com)