For example, using a cyanoacrylate adhesive to saturate areas ... [blackfish] even uses a peeled piece of cardboard — exposing the corrugated part — as a set of detents (6:56) to retain ...

First, a sheet of corrugated cardboard is made out of three sheets of ordinary Kraft paper. Paper and glue are relatively inexpensive, so cardboard is inexpensive. And compared to a sheet of paper ...