This is the fabled mini-greenhouse, by request.
To make your own, you will need:
8 square wire-mesh panels for cheap modular college-student shelving
12 plastic connectors that go with the above
1 flimsy translucent tarp
1 roll packaging tape
3 8-inch acrylic rods or something similar
1 fluorescent light fixture with 24-inch bulbs
1 measuring tape
I won't spell out the step-by-step instructions here, because it should be relatively clear how this was done, but essentially, I assembled two cubes' worth of the shelves, measured them carefully, measured and cut out plastic to fit around this, and then used packaging tape to tape the tarp together around the frame. Stick a light on top, tape acrylic rods to the opening flap to weight it down, and voila. More or less.
The original intent of the thing was to serve as a high-humidity enclosure for trying to grow cuttings of a Davallia trichomanoides. The cuttings have, for the most part, not taken (I've had difficulty remembering to water them, though I haven't given up on any, either, and it looks like some of them actually are taking, just very slowly), but even so, it's worked well for growing other sets of cuttings (Begonia, Pedilanthus tithymaloides, Senecio macroglossus, Haworthia, Dieffenbachia, Cordyline fruticosa, Ficus maclellandii, etc.), and it was easy enough to make. I put it together in an afternoon.
According to the thermometer and humidity gauge (admittedly a very low-tech humidity gauge), this normally keeps the plants inside at about 70ºF and between 60-70 percent humidity. Though the humidity level can get as low as 40% if I'm not paying attention to the watering, or if the plastic front is a little more wrinkled than normal, or whatever.
I had had a pre-made mini-greenhouse before this, something with a watertight plastic tray and a plastic dome that fit over it. It was perfectly nice, but I outgrew it quickly. My self-made one gives me a couple more inches in height than that one did, and close to twice the surface area, and it's sturdy enough to support a light, so I can get a little more light on them too.
Something you can't really see in the pictures is that the shelf above this whole contraption has mirror tiles on it, facing down, so some of the light gets a second chance to land on a plant. There's a mirror outside the box on the Dizygotheca side, too, which you can kind of see in the first three pictures.
It's not that big of a deal, not something I would have thought to make a post out of if not prodded to do so. If it gets as dry in the apartment this winter as I think it's likely to, I may actually need another, though let's hope it doesn't come to that, because I don't have anyplace to put one. In theory, of course, pretty much any frame you can wrap with plastic should be capable of doing this; this just happened to be a really simple shape to wrap, and it's handy that it's got a solid top and bottom.
The only down side I've discovered thus far is that this doesn't allow for any real air circulation, which has led to some unhappiness among the Dizygothecas in the pictures (the pictures were taken before I discovered that they were unhappy). But it's always something.