I used my Cricut Expression for the squares and numbers. If you don't have a Cricut machine, you could use a 2 in square punch for the smaller layered squares and a 2 1/2 inch square punch for the bottom layer. You can use, and I recommend using, stickers instead of Cricut cut numbers. Another option would be to use the negative image from Cricut cut letters.
Then I used magnet strips. I found these at Michael's and found they worked best.