I think actual game play would work best with felt and velcro.
Step one: three and a half pieces of paper. Fold.
Step two: color. And color. And color. Oh god so much coloring. Black should be opposite black.
Step three: mobify.
To be honest, my original motivation was my feeling that pawn promotion is a bit of a copout. This seemed the most interesting way to do away with it.
Final product:
P.S. This is basically what I'm envisioning for the diagonally looping bishop variant. Just imagine eight columns with the usual two color pattern.
