I added an accent color and the logo from the matrix digivolution card in Digimon Tamers. I also put the circuit pattern to more areas as well.

You will need 4 - 6mm x 2mm magnets. Here are the ones I used - Amazon.com: VNDUEEY 300Pcs Refrigerator Magnets, Small Magnets, Fridge Magnets, Whiteboard Magnets, Tiny Magnets, Round Magnets, Mini Magnets for Crafts, Miniatures, Nails, Office, Kitchen : Industrial & Scientific