yeah, but its not really needed. at least from what ive seen on a few tanks now. as long as its fully supported in all 4 corners, your golden. (and level LOL)
to make one like this, you would need some eggcrate, sheets of acrylic, plexi, lexan. glass even. just section off each partition, give room for skimmer in first chamber. then flows into refugium section. then into return. You can find tons of diy plans on the net for individual sizes. Eventually ill get pix up of my 20 gallon long converted into one.