Be loving, be kind, and BE NYC! If I have to stop this train, you'll be in big trouble, mister and missy. :)
These are designed to use 12x3mm round magnets, glued in post-print. One for each, except the Y, which has two.
You'll have to rotate the objects in your slicer so that the back-side is on the bed. I used supports for the background pieces, to accommodate the somewhat large magnet cut-outs, but you may be able to get away without them. I also used a 3mm brim for better adhesion on all the parts, but you may not need them.
FrankenMini (modified MP Mini)
Inland black and red at 205C.