This is my 3rd iteration of a magnetic, modular go board (mostly to play a popular 5 in a row variant). Easy to print! The box takes most of the filament. This uses 3mm by 2mm magnets ($9 on amazon for 200pcs). The magnets can be tapped into place with a hammer and do not require glue (ymmv based on tolerances). Print 1 of each plate and then a second of the plate of pieces.

If you don't have an AMS, layer changes at height is perfectly suitable for this model, aside from the lettering in the box lid.

The cutouts in the side of the box are to allow removing the board from the box. If I were to pick one thing to improve in the model, I'd redesign the lid to slide into a groove from the side instead of fitting over the top.