I tried an idea that I had in my new 65 gallon tank and it turned out great. The idea is really a spin off thing that I have saw other do, Graphixx being one of them. I call then Rock Racks.
I knew that I wanted good flow through in my new tank and a lot of caves and bridges. I also wanted good strong structure for the my live rock. Here is what I came up with.
Step 1. I built a rack system out of standard 1/2" PVC. I made sure to leave the ends open to allow air out and water/critters in. Also leave enough room in for the foam skin. One thing I feel that is important is to make "cube" frame instead of just a "table" frame. The foam skin is extremely buoyant. Without the cross pieces on the bottom of the racks to anchor them in the sand, the whole thing can come up out of the water.