Used SVG's of some common mariokart power up items to make double sided xmas tree ornaments. I edited the SVG files to add the slot on top, modeled in CAD and cut faces to allow selection for color painting using the bucket tool easily. This was made specifically for AMS/MultiColor machines. I did make them two sided but you can just erase the painting and do your own thing. The bottom will print fine if you don't color it.

I myself used ABS, I'd recommend that or PETG/PLA Tough. Regular PLA or Shiny PLA would look just as good or better but I would thicken it up a bit so it's not too easy to snap if you do.