miomantis paykulli (egyptian mantis) Phyllocria paradoxa (ghost mantis, I think I spelled the latin name wrong) ant mantids, and gambian flower mantids can be housed communally, so can stick manids (pretty rare), but anything else will cannibalize each other. just make sure you always provide food.
some species can be successfully housed together to near adult stage. a properly prepared small plastic container would probably make a better cage than a screen cage, most need fairly small containers (less than a gallon in most instances. like chameleons, you are probably better do some homework before you start. more and better info can be found on mantidforum.net jmo