Compatible with 65mm Hex Tiles, such as Hexton Hills tiles.  Based on the OpenForge magnetic base for 1" OpenForge floor tiles: https://www.thingiverse.com/thing:2740279 I would have added the OpenLock connector, but it wouldn't fit between the magnets.

My original design (v1) used 12 magnet balls per tile, but after printing a test piece, I realized that it was unnecessary as the hex tiles didn't need to align on a half hex (unlike 2x2 dungeon tiles aligning on an offset).  So in version 2, each tile only needs 6 balls.  If you want a stronger magnetic force holding the tiles together, try using version 1.

Use 5mm magnetic balls (aka "Bucky Balls").  They can been found relatively cheaply on Amazon.

I would suggest placing the base on a steel plate so that it holds the magnets down.  Glue the Hex Tile onto the base with super glue, making sure you don't get any glue on the magnets, they should be able to move freely after you've glued the base down.  The ball magnets will auto-align with each other when you move the tiles close to each other, so no need to worry about aligning the poles correctly.