I'm making several individual terrain tiles inside of blender for use within a Unity 3D 5 game. Each tile is square and is made to represent a segment of a world. In game the tiles are randomly* chosen and placed between each other. However these tiles do not always have matching sides.
Why the tiles
To allow for greater terrain sculpting possibilities such as caves, precision-placed landmarks e.t.c. but still allow for a procedurally generated feeling; randomly placed static tiles are used.
There are mountain tiles and there are plane tiles. Mountain tiles have a more extreme terrain and are mostly next to other mountain tiles so that bigger mountains can be formed. Plane tiles are similarity placed next to other plane tiles.
The game is "low poly" and so is the terrain. This makes it hard to have flat sides on every tile at the same height for easy "stitching".
How can I match these edges runtime to ensure that there are no visible tile edges?