- Save your game as a backup beforehand. From the "Terrain Tiles Archive" chest (just right of the terrain card slots), take a bag.
- For each piece of 3D terrain you wish to add, remove the corresponding piece from the bag. It's fine to only replace some pieces.
- Change the name of your 3D terrain object to exactly match the piece you removed.
- Change the "GM Notes" to "Terrain Tiles", again this must be exact. To change GM Notes, you must be the black player (GM).
- I recommend turning off snapping on the piece, as the mod will automatically snap terrain tiles.
- Put the 3d piece into the bag.
- Once you've done this for all terrain pieces you wish to replace, right-click on the "Terrain Tiles Archive" and click "Reset".
- Drag and drop your terrain bag (containing the new 3D pieces). At this point you're done: try a showdown that has terrain to make sure your tiles are spawning.