Some folks have asked about the best way to integrate lava rivers (using lava river tiles) into regular-painted Caverns. One great way to do that is by using the banks pieces (available both in KS6.66 and as part of KS6). Banks with either the lava or the caverns paint scheme will work for this.
To do lava river using Caverns banks, first lay out your lava river tiles and surround them with a few flat lava floor pieces. Then, build the surrounding cavern area one floor tile higher (using extra floors and/or our new foamcore risers underneath) and transition down onto the lava area using the Caverns banks. This creates the effect of a "lava rift" in the cavern floor.
Alternately, build a wide flat cavern floor. Then build your lava river on top of it, and use lava-painted paints around it to transition down on to the regular cavern area. This creates the effect of a lava flow that has run out across the cavern. (This method also works if you want to build on top of our new light panels... lay out the light panels, place caverns floors around them, and then cover the panels with lava river tiles and lava banks.)