This is part 2 of the Metal Computing series. See Part 1.
Here's a drawing of some supports that can be put together into modules. They are made out of 1/2" x 1/4" stock.
The square holes on the sides are for the 1/4" x 1/8" rods, with a little extra room to allow for clearance. Each level is 1/2" apart. Holes run vertically through the sides so that the whole thing can be secured.