This ancient roman game is pretty darn fun for how simple it is! It's like tic-tac-toe except after the pieces are down you start moving around the board.
Rules:
Two players each get 3 pieces Take turns putting one piece down Once all pieces are down, take turns moving one of your pieces one space (you must make a move) The first player to get three pieces in a row (around the circle or through the middle) wins!
This model uses 15 6x3mm magnets. Here are some very affordable ones
I also used E6000 adhesive to affix the magnets
I printed the board top side down and swapped filament at 1mm to get the two color graphics.