OK. I'm not the first one to do this, and this may not be the best way to do it, but I did it.
First, I figured out whether or not this thing would hold enough prints to be worth building. I determined the maximum height the rack could be (taking into account the garage door opener in the middle of the room) and settled on 6 feet.
Next, I figured out if that 6 feet would allow approximately 30 shelves. That doesn't sound like a lot, but I didn't want to crowd them in too much, and typically by the time I do 30 prints, the first prints are already dry, so I can layer them up on the rack and it should be fine. Proceed.
The sketch looked like this:
I bought a mess of 2x4s to build the frame. I clamped them together and measured 2" increments to mark where the notches would be cut:
The marks are on the edges, but the notches were cut on the wider part, or face, of the 2x4. FYI.
1x2s might have been sturdy enough, but I didn't' want to get to that point in the project only to find out that they weren't, and have to tear it apart and build it again. If I build another one, I might use 1x2s.
Next I set my tablesaw to 1/2" and ran the 2x4s through, scoring them every 2 inches. The blade makes a 1/8" cut, for the 1/8" hardboard (masonite) pieces that I picked up at Lowes. I had the Lowes guy cut the 4' x 8' sheets into six equal 24" x 32" panels so they could fit in my car. This is also the most efficient size as you get the most pieces from a 4x8 sheet, and it's big enough to hold one poster comfortably, and 2 with some hanging-off-the-edge.
Then I build the top and bottom, to which I would attach the scored 2x4s:
With the frame assembled, I start sliding the shelves into the notches:
There is a 1x2 in the middle of the rack to cinch the frame together, as some of the shelves weren't nestled in the notches as far as I would have liked:
Eventually, I re-did the rectangular frames which pulled the whole thing together more tightly, pushing the shelves into the grooves better.
These are 3" rubber casters. They seem a little too soft right now, because they don't roll very smoothly. But I'm thinking they'll loosen up over time.
This will save me a short walk across my studio to where I had a wire-with-binder-clips-drying system. Those few steps with every single print add up, so I'm hoping this will speed things up. It ended up costing about $75 or so in materials. So there you go.