That's exactly what I did. I got aluminum angle stock from Lowes. Can't remember the exact dimensions but it was 6ft long. I got 3 pieces of it and some nut/bolts for $14 and some change. My setup is 16 inches wide, 13 inches deep and 9 inches tall. I have 3 5830s in it now but could easily add another 1 or maybe 2.

Here is a pic...