Made it in an hour or so; not perfect. It works by centering itself on the wet side's opening, and the back of the guard rests against the glass. When the pump is on the suction keeps it centered and attached to the pump. So it's easy to remove and put back on without having to worry about whether or not it's centered or covering the entirety of the pump like a foam guard. Experimenting with the hole size and density but for now keeping it small like that for maximum protection.