All files are supportless prints.
Just for fun, have been creating magnetic boxes from terrain data. This one is the Tetons in Wyoming. The lid is printed in this vertical position for maximum terrain definition/detail and so it can be printed supportless.
Comes with three different types of bottoms. One for games like D&D with an area for dice and other items, another that is split down the middle with a divider for any ranbom things, and one with just plain openness.
Made for 6x3 mm magnets. I got some here for $14:
Examples printed at 0.2 mm line height and 15% infill. I would recommend not doing less than 15% infill, it prevents warping of the lid so that the tops and bottom fit together good.