I used to print my custom-made signs on regular copier paper with my inkjet printer, but noticed that as the ink settled into the paper it made the edges of the lettering fuzzy. I now print them on glossy photo paper with the same printer. After mounting them on the sign backing (made from styrene), I give them a dusting with Testor’s Dullcote. It does two things; protects the images and kills the sheen of the photo paper.
LION prints his on a color Zerox machine, and mounts them with silicone caulk.
ROAR