You know, there never seems to be enough of the right kind of space in a jewellery box, from what I've seen. I think it would be both neat and useful to have a modular system where different tiny boxes clip or stick together to form one large box that can expand or contract into sizes, shapes and configurations far beyond its original arrangement. Of course, it's probably not going to be quite as pretty as custom-made, one-size-fits-all boxes, but maybe you can make the pieces out of wood with magnets embedded in them, to keep it looking good.
Mokalus of Borg
PS - Or keep it simple and just use stackable drawers.
PPS - And probably some dividers inside the drawers, too.