I thought perhaps some might find this interesting or useful. This caterpillar-rearing cage was made by a teacher friend, and apart from cutting it down to about 14" (she had it at more than 2' tall, which I found hard to manage), I haven't found it needed any improving. The jar inside has tin-foil over it (so caterpillars don't fall in), holding one or more florists picks with fresh host plant foliage in place. Top and bottom are old cake pans and sides are wire mesh. Very easily disassembled for photography and cleaning. Easy to add a stick for caterpillars to pupate on, though they will happily use the top pan and the stems of the host plant, too.