First I simplified the pattern; the more complex version can be found with a quick Google search for "aztec calendar" or "mayan calendar." I decided 16" across was about right, and I found a random piece of masonite to cut down with my Dremel for the base of the mosaic. The center, where it goes all 3-d, is a simple glass plate from a dollar store turned upside down and glued to the masonite with silicone. I modgepodged the pattern to the inside of the glass plate and traced out the basic pattern on the masonite with a Sharpie. Then the gluing; it took about 20 hours. There's a hole drilled into the back, under the upturned plate, so you can hang the piece on a screw or nail. It is grouted with charcoal DiamondCrete (that adds a lot of strength, and weight). This piece was made as a donation to a charitable art auction.