What you will need: Approx. an 18in square piece of foam for each plaque A head or face of some sort. I found these at a Halloween store. Gray paint Black paint 4in bolts w/nuts and large washers.

These are pretty easy to concoct. First fold a piece of paper(as big as your piece of foam) in half then draw and cut out 1 side of your plague. When you open it you'll have a full pattern for your plaque. Now place your pattern on the foam and cut the foam to it. Now tape off the edges and dig out the inside foam (the spray paint will only eat away approx. 1/2 in of foam and you will want at least a 1in deep cavity). Don't dig to deep, when you paint the cavity, the paint is going to eat away the foam. Now spray the inside of the cavity with your black spray paint. Once the black paint is dry, remove the tape off the edges and paint the remaining foam gray. Once the paint is dry, make 2 small holes for the bolts and run them with washers through the cavity (make sure the bolts will be covered by your item that goes inside.) Now that your mounting hardware is ready you can mount the inner face or item inside. Just be sure to test any glues before using them on foam. A heavy duty silicon was my choice. Now mount them through a wall and you're ready to go.