After a couple of months and some trial and error on their part, I recently received 16 custom made caves. These things are awesome! You can’t see them in the photo of my 75g tank (see the post What is my set-up? Pt. 1), but the entire understructure of the rock work is made with these caves, allowing numerous tunnels under the rocks.
I highly recommend the company, even if you don’t want something custom made. They stock a wide variety of cave types for plecos, cichlids, and other aquarium inhabitants. They also sell driftwood, Xtreme brand fish food, and other products. Visit their website and place an order. Tell Brantley and Jodi that I recommended them!