Use quarters, nickels, washers...
All good ideas....I'm trying to keep the gill plates clean of overspray, etc. when spraying sides, back and belly. Was using frisket to do this but its a PIA to cut out for every lure. I took some clear plastic and traced the gills of the lure then used those images to cut a plastic playing card in the gill shapes...just position them over the blank, secure top & bottom, to hold them in position, and spray away. Makes a clean gill edge with no mess. I've read you can do this with sheet foam from Michael's too....just don't have any handy.