Masterwork Tools
Short Description
Masterwork Tools was founded by Devon Jones. Evan Carothers (EC3D) also releases items through it. His biggest claim to fame, is the incredible Open Forge set of terrain. These are fully free (from Thingiverse) dungeon tiles. They are Openlock compatible and the bases even have spots to put in bucky ball type magnets to hold them together. (Personally, I use these bases, and scale them up to wylock scale).

Beyond the Open Forge tiles, he has all kinds of other terrain pieces as well.
Thingiverse Profile