Strange, with 16 gliders in five different colonies, I've never had one chew. I think good air flow is important, though you do need to take each individual glider's behaviors into account when choosing a bonding pouch. Just remember to be really careful that they don't overheat in the summer without a window in the pouch...it really is a serious concern.
I also make my City Pouches, which look sort of like a small purse. There's a flap over the screen with a magnetic snap, for gliders who are disturbed by light that might come through the screen. I'm really so busy with work, I have not made one of these in months. However, here is one that I made for Sariyappa: