Best of all, I made it at TechShop.
Step 1: Equipment and Materials
2. Metal sheet (which can be found at most hardware stores, or at several on-line sources, or pre-cut metal plates which can be obtained from a trophy shop). Brass, copper, or aluminum would all work.
3. Paint. I used black spray enamel for my plates, either glossy or flat, depending upon the look you want. Dark brown would work too.
4. Graphics software. Either to manipulate an existing image or to create your own.