This is kind of like the "Endless hallways" ceiling discussion thread.
I have built a drop ceiling frame (see link) and now pondering on how to cover it.
I have a roll of 20"x100" Black Plastic (easier to store but I bet it sags), I have a black 10x20ft EZ Pop Up Canopy Top Replacement (it's complicated), but also have my eye on Home Depot 10-Pack 4'x8' Corrugated Plastic Sheet for $140 (less sag but takes more storage space and have to paint it because the other colors are 2 times more expensive.).
Any one have any experience with the Home Depot Corrugated Plastic Sheets or have any other ideas?
I expect Kindo to recommend foam, bfjou812 to "make" me buy a new tool, and J-Man to suggest something that involves an oscilloscope
http://www.snydercentral.com/halloween/static_props/garage2018/garage2018.htm
