I would go with the latter if you’ve got the room for it, more floor space is better than space split up into different smaller levels (:

Oh my gosh please ignore the duplicated posts lol

I’d think so as long as there wasn’t anything they could jump onto to jump out, maybe keep the room bunny proofed until you feel more confident they won’t get out?

I found that my bunnies aren’t happy with less than 4×8 surface area. And that’s one level – not combined. I like the NIC cubes because you can experiment with sizes and designs, and change them up, and find something that works. I use 2 panels high. You could use some of the panels to create an overhang so they can’t hop out, or you could enclose it like the one you looked at on eBay. I used the panels to create storage on top of the rabbit condo. So the roof of it serves as the storage space, which is 1 panel high. So 3 panels high in total. I store light weight things such as hay, puppy pads, etc. I don’t have mine on wheels. I just have 10ml plastic over the carpet, then puppy pee pads, then a combo of towels, and veterinary fleece bedding. I suppose once you have found a design and size that you are really happy with, you could ask someone to help you make a wooden base of it. It would be easy to do yourself even. Get a sheet of plywood, ask them at the hardware store to cut it to size for you. If you use a 4×8 size, you could just buy 1 sheet of plywood and hot have to cut it.Get 4 furring strips (1/2″x1.5″) to border the base. Get caster wheels from the hardware store. Screw them into the underside of the plywood floor. Just leave enough length on the furing strips that the corners meet. With a miter saw, you could get the 45 degree angles. Even without a miter saw, it’s an easy enough project with a drill, wood glue, a handsaw, and a few screws.

I like your idea of putting a NIC cube setup ontop of a CUBE – for storage. On my second floor of the NIC setup, I put a floor of cardboard, covered by fleece bedding/towels. That way the cardboard floor is easy enough to replace if they soil it, and light enough not to require extra structural support.