"I've used the same idea (one piece folded to 3D shape) for my bicycle frame packs. I use a natural colored (no color) coroplast material. Lightweight, strong. 15.7 liters of storage with a 3.5" wide cross section."
"The handlebar packs look great but no room in my case.I 3D designed, cut and folded these two (above and below bar) "coropacks" out of two pieces of coroplast to fit my bike.Bike purists turn up their noses but i say function over form for me."