I've never worked with trimcap.
Oh dear. This will at least be an easy one to learn on. Call your distributor, order some trimcap, I like channelbond typically but the guys have been using weldon, at any rate you'll need glue. Also a big fan of poly over acrylic for these, polycarbonate can take a beating, acrylic stays white, pick your need based on that. Remove the old face, trace onto new polycarbonate face down with a sharpie (poly has a back side, make sure you put face down on the back, cut right on the line, decorate, then trimcap. Easiest (cheapest?) way is to get a piece of plywood, put 4 nails down to hold it in place. then start putting the trimcap to the edge, adding nails every 1" or so to hold it tight to the plastic, trace with channelbond, allow time to dry, 15 minutes or so, and do 3 coats. Carefully remove the nails after a couple hours, slip it over the can, add new screws in totally different places.