I am trying to make a hanging shelf/sculpture out of a bunch of individual wooden hexagon containers. Each hexagon is about 3" across the opening, the pieces they're made of are 1/4" thick, and they are some sort of lightweight balsa/pine wood. I don't have a staple gun that would fit into the containers to attach them together and any staple would need to be 1/2" long or less. Is wood glue going to be enough to withstand the pull/weight of the hexagons on each other while they're hanging on a wall?
Wood glue should be fine here, assuming the pieces are unfinished. In fact, in such thin material I think that wood glue would actually be stronger than most mechanical fasteners (anything short of bolts with washers). However, I would make sure to mount it in a way so that the places where there are only one connection don't get stressed.
More specifically, I would apply a thin coating of wood glue (i.e. titebond 3) to both faces to be glued together, then clamp them in place with a spring clamp.
Another thing to consider would be to make a backer board in the overall shape of your piece and attach each hexagon to that board in addition to attaching them to each other.