Guitar Rack
This is the rack for guitars in their cases that I built using components from Ultimate Support systems.

NOTE! As of May, 2006, it looks like the link above is broken. It connects to Ultimate Support's main page. I guess the "ThinkerToys" division wasn't so popular. That's a shame.

MORE IMPORTANT NOTE! As of July, 2007, you can no longer obtain these parts from Ultimate Support. From an email received today from Ultimate Support:
Unfortunately, most of the sku's used on the rack have been phased out. We still use aluminum tubing, but no longer sell individual lengths of just tubing. The leg bracing sold separately has also been phased out. You can still purchase the TFG-150 t-fitting (90 degree angle fitting) and the unf-150 (used to attach leg bracing).
So I guess that's the end of that. If anybody finds another way, please let me know and I'll post it here!
Overall View

As I assembled it, the guitar rack holds six guitars in their cases.

The overall height is about 44 inches to the top of the guitar cases. The overall depth is about 29 inches. I used tubes 48 inches wide for the rails that support the guitars.

Assembly detail

Detail of the assembly of the rails that support the guitar cases.

Side view. The rails that support the guitars can be any length, within reason.
Here are all the pieces I used: The total cost was approximately $210.