My ex was a carpenter for Ryland homes (cheap construction, CHEAP materials, over priced pre-fab houses)! He used to bring home end rolls of off brand stuff that was like tyvec. No printing, solid white. We'd tape & staple sheets of it from the ceiling to form a tent around the grow. Shit worked great, & my favorite price. FREE! I love cardboard too. Pretty rugged, & takes paint well. You can reconfigure your walls to conform to ea grow, more practical than plywood. Paint? One coat for cardboard, 3 coats for plywood. I use white tyvec type for putting things like this together. White is good, but it like it because it keeps its tack even when wet. Purchase price a little bit more than duct tape, but you don't have to ever reapply, it sticks much better. I like your set up, practical, functional & not over priced!