UPDATED NOTE: These parts were designed back when hobby 3D printers were in their infancy. Tolerances were not great so snap-together designs weren't reliable. That is the reason for the loops and magnet design. Today, with the great advances in 3D printer technology, we can print much better and more accurate designs. For example, I've started releasing a new set of 3D Printable Modular Dungeons. https://www.thingiverse.com/thing:3333475
Instead of re-inventing the wheel, I've designed the parts to use OpenLock. However, I've moved away from walls. They look great in photographs, but sure are limiting when actually using the pieces. They take longer to paint, are more difficult to work around, require more unique pieces to make the same dungeon layouts, and maybe most importantly, are more difficult to store.
So now the trick is to make floors that are identifiable as various terrains, and figure out ways to attach components to just the floor. I have a great design for doors, I just need to release it. I'd like to come up with some designs for traps and torches as well.
Improving on the parts located at http://www.thingiverse.com/thing:2998...
I have printed multiple parts together (combo files) and the gaps are so small that the parts are joined together during printing. I think they could be broken apart, but I like them joined.
I will upload a zip file of the parts in STEP format so people can easily modify the designs. For example, you could combine different pieces and then print them all at once to save time and make the whole thing a little more sturdy. I have stl files of three combination pieces included. (2x2_combo_straight, 2x2_combo_doorway, and floor_2x2)
More parts as they become available.
Print whichever pieces you want. The floor pieces hold the wall pieces down. For large areas of floor, there might be some small gaps depending on which floor tiles you use.
For the door, I use a piece of paperclip as a hinge pin. If you have a drill the correct size, drill a hole in the doorway and the door to match. If not, I just use wire cutters on a straight piece of paperclip and leave the "bit" in the hole when finished.