Print the whole alphabet, delete the characters you don't need or duplicate them as you like.
The back hole is a perfect snug fit for a 10mm round magnet.
I've used these cheapo magnets, but any 10x2mm magnet will work.
https://amzn.eu/d/cb0T0UK
How to print multicolor tiles (using Prusa Slicer):
If you want to print in just one color, you might want to use the .stl file.
No supports needed.
The author marked this model as their own original creation.