I have Celastic and I do not have craft foam, Celastic acts like cardboard until it gets wet with acetone, and becomes wet cloth til it dries, then acts like tough plastic. The tricky part is the filters, and I think open-cell foam with its complex "tunnels"would work better than similar pore size cloth but do not have atm.
@Livein3D found a source for straight N95 material. yay 