Spike 
Now on to the metalworking bit, the shelves.
I used some 2"x.250" wall 6061 Aluminum Tubing for the center support, and some 1"x.120" wall and 1.5"x.120" wall 5052 Square Tubing. Oh, and there's also some aluminum rod in there too.
Since it's going to an art gallery, i figured the shelves should be a little bit of art themselves. I wanted a minimalist look, so that means over-simplifying things. That means as few supports as possible, and trying to make it look like it's not able to function as a shelf. That's why i picked the .250" wall tube for the upright. It's strong enough that i can use it as the only upright, and it won't bend and flex.
And, since I'm determined to make everything as hard as possible, i decided that all the supports needed to be elegantly curved. That makes the actual shelves themselves the only flat and straight pieces on the shelf. Verticals are curved, horizontals are straight.
On to running everything through the roll bender. Maybe one day i'll be able to justify the cost of motorized/hydraulic machine and i won't have to spin the wheel all day to do this stuff.
First things first - Annealing. When bending aluminum tubing this thick, it's a good idea to anneal the tubing first. Annealing isn't nearly as big a deal as it seems, and it will make your day so much less frustrating. Annealing will help the tubing roll through the bender easier and come out with a smoother arc, as well as making the work of bending much much easier on the biceps... Also, it will help minimize the chance of the aluminum tube cracking on the outside edge of the bend. 6061 -t6 doesn't much care for bending.
This is a snap if you have an Oxy-Acetylene welder handy. Use a welding tip, not one of the useless rose-bud tips. Set up a sooty flame and cover the tubing in acetylene soot, then adjust the welder to a neutral flame, or just a little past neutral and go back and burn allt he acetylene soot of the tubing. The acetylene soot will burn off at 900 degrees... convenient since that also happens to be when the aluminum will anneal. Let it cool and you're good to go with some nice buttery soft full annealed aluminum tube.
It will work harden as you bend it, and i ended up having to re-anneal about halfway through the bend.
After the 2" tubing i ran my 1.5" square tube through the roll bender the hard way (like a diamond, not like a square), no annealing needed here because it's a softer alloy and thinner wall.
I cut my tubes into the appropriate sized arches, and then notched my 2" tube to fit the square tube, and welded it up and ran a stick of round rod between the legs of the square tube to give some rigidity to the arched foot.
Repeat 3 more times and tig weld everything together, and the bases are all ready to go. Next up is fitting and attaching all the shelves to the bases.
