masonite board (or foam core, wood, chipboard)
black acrylic paint
black poster board
mirror mastic (optional)
thick clear glaze (Diamond Glaze, Crystal Glaze, Glazed Dimensions)
old credit card
square paper punch (or scissors)
brayer or piece of plexiglass
Glue funnies to a piece of black poster board. Smooth down with an old credit card (hotel key was used here). Punch or cut out squares.
Position the mirror where you want, on a piece of masonite that has been painted black. Make a light pencil sketch around the mirror and remove. Glue on the funny paper squares with white glue. I paint the glue on the masonite, let it almost dry, then stick the paper down. Leave a tiny gap around each square. The squares will curl up a bit. I found that I could flatten them out by rolling them with an acrylic brayer (roller). The author suggests using a piece of plexiglass and weighting it for a few minutes with cans from your pantry.
Glue the mirror onto the board. As mine already had a flocked backing, I was able to use plain white (Elmer's) glue. If you just have the silvered backing you might want to use a mirror mastic so that the glue won't eat through the backing causing strange looking blobs. Then either use thin pieces of wood, or in my case, cut 1/4" wide pieces of matboard and paint them black. Glue the slats around the mirror and the outside edges for a finishing touch.
The author recommends that you seal the paper with decoupage medium (Mod Podge) then several coats of varnish. I used a clear glaze (this one was called Glazed Dimensions) directly to the paper. It's prudent to test your sealer and/or finish first before slathering it all over your project. This tends to eliminate the "oh no" moments we crafters know so well.