I imagine if you asked Brantley would make what you need; he did for me. He might even make them in different colors. My RCS were all over the towers and then, suddenly, it was as if they figured it out and three popped into a hole. Now it's like they're playing.
Guess I'm going to have to get a 20L and divide to accommodate the tubes, towers, driftwood, plants, oh, and the shrimp and Si and Willie, the Bettas. :-D