Also, I was reading through another "trashcan armor" type thread on Mandalorian Mercs using sterilite storage tubs that suggested oven baking the plastic at 300 degree for ~2 minutes to get it maleable (depending on the thickness).
Also, bit of a recommendation for some of the "scraps" that are invariably going to exist (including, depending on the style of your can, the curved "lip" of can/bin/container. -You've got to make the finger-armor pieces out of something, why waste plastic?
I know there are methods of doing ity bity rivets, so I can't imagine the cost going up much. Anyone more familiar feel free to correct me though.