I put a couple L2 Pseudocreobotra wahlbergii in them that I got from Paradoxica. Had to take out all but one clump of moss so I could monitor them effectively though. I think these would work well for quite a few smaller species, and juveniles. I could have probably also made a background with gaps & cracks, and such, but I'll leave that for another time. I was kind of thinking of making some slightly larger ones using glass, so that they resemble art work.
D-Hemptress you should definitely try it if you're tight on space. That's the main reason I came up with this.