I built a garf type plenum for my 40 long refigium out of 1/2" pvc.
Since I wanted live rock in this tank I decided to integrate a rock stand, the stand looks like the one found at
http://scubaraven.com/100_reef.htm.
Connecected on that I build 2 small reef frames ( 1 for each side ) like what is found at
http://www.krob.com/aquarium/Aquascaping.htm.
So far I only have one of the frames in the tank and am slowly working on the other side. Since this frame is rather small, securing base rock in a way that leaves room in the tank is like a hard game of Tetris. Using nylon ties, a masonry drill bit and even a drimmel to shave down areas of some pieces for a better fit... all of this is a big PIA. It would be much easier just to pile them up on the pvc stand and forget the frame. That is what I plan to do on my larger tank when I get around to setting it up.
I think that this is a great way to maximize the surface area of the sand. Yes, some points of rock do touch the sand and the critters have no problem getting up and down.