Mod is based on imarunner2's pvc bike rack.
Step 1: Parts List
I bought two 10 foot 3/4 inch pvc pipes and had them cut in half at the store.
11 3/4 "T" connectors
2 sections of self adhesive insulating pipe foam.
Pictured is my dog wondering if the foam is edible.
Step 2: Measure Twice Cut Many
I started by building the base first. I used 4 elbows on the ends to give it a slight off the floor elevation. Here is an example pic the one side of the base. I've dry-fitted the rubber insulation foam. This is where the lower bout of the guitars will rest.
Step 3: Assembled
The rubber foam is very cheap-less than $5 for 6 feet. It has two self adhesive strips on both sides of the slit. It is very sicky so care is needed when doing the final fit. I used PVC cement on the top elbow joints-didn't want to risk it popping apart and dropping the guitars. I measured for 6 inches between the teeth for the archtops and 4 inches for the other two slots.
One improvement you should consider is adding a cross support halfway up the back. The unit is fairly sturdy now but does have a little sideways looseness.
Whitman still can't figure out if this is food, a toy, or what...
Step 4: Done and in Use!
Here you see my Ibanez, Heritage 575, Hagstrom Swede, and National Delphi filling it up. (yes they're all left handed)
Total cost was less than 30 dollars. Similiarly manufactered items go for $50 to $100 in music shops.