I also decided to alter the cavern river tiles by @Lifeburn and make them openforge 2.0 compatible @devonjones. I also remixed the basic cavern tiles https://www.thingiverse.com/thing:3516425 and the graveyard tiles https://www.thingiverse.com/thing:3518744 by Lifeburn so check that out too . I used the same principle here, and basically just removed the default bases. Now you should be able to combine this tiles with any openforge bases (2x2). I also redesigned the rivertile edges a littlebit so that they fit a littlebit smoother in between the other cavern tiles. Let me know how these check out!
EDIT: I smoothened the edges of the narrow rivertiles a littlebit, so they better fit together.
All the credits go directly to Lifeburn for designing those awesome tiles! I just edited them a littlebit, because I liked them very much and wanted them to use them on my game table alongside my other openforge 2.0 tiles.