You realize the only 3 cubes you will be able lift down and work on will be the 3 top cubes which are 5' above the floor. The top cubes would have to be moved away before you could access the 2nd row cubes and so on.
If you plan to take the top cubes down to use as a work table or something, they would need to be kept empty for ease of use.
Something to think about.
I'm not sure I actually thought about this. Thanks! I guess I was unconsciously thinking of having big, light stuff in (maybe 4 or 6) bins (or some other smaller containment) on the top, empty it, take it down, refill it. Then reverse the process to put it back. It's kind of a pain, but for infrequent use, and not it's primary use, it makes for a lot less furniture, and only one project. The trick, then, is to ensure the stuff stays contained. I suppose, given that, it probably wouldn't be that much more difficult to take out a few pocket screws to separate them.
I'm having a hard time understanding how just connecting a couple of these:
could make them stronger. A steel plate screwed to the edge or side over the separation, I get, but just connecting the top to the bottom isn't making sense to me somehow.
At 55 pounds per sheet of plywood, though, just 3600 square inches (30*30*4) is about 43 pounds of wood. I'm having seconds thoughts about adding pounds of steel hardware. The 24" option is looking better.
I'm off to the shop today for the 24" test box. I tend to over-shop, meaning I put in way too much research for inconsequential product. As much as it counters my nature, I'm sticking to big box, and what they actually have stocked. (Deep breath.) This could turn into a forever pursuit and shopping time-suck if I don't limit myself.