Like a lot of folks, I prefer the lower-detail "Dungeon Tiles for Miniatures Gaming" by Telvin_3d over the lumpy-bumpy floors of the OpenForge Tiles.I created a couple of doors and "stair" elements to use with the system. The .stl sizes are a bit wonky, but if you rescale everything to be 50mm in the z-direction, the pieces should fit perfectly with the originals. This was a pretty quick build, so the edges and alignments aren't super-clean and consistent, but it's good enough for my purposes.