Your assistant gets into an empty cubicle which is so small she can barely get in. Close the cubicle and run a big metal plate through it. This plate cuts the cubicle and your assistant in two. Now pass two long, hexagonal tubes through the cubicle, one through the top, one through the bottom. These tubes are empty, the audience are able to look right through them (and therefore right through the cubicle). The spectators start to get really worried about your assistant. But there's no stopping you now. You even push the bottom of the cubicle to one side so that there's nothing between the top part of the cubicle and the small table on which she's standing. Now push the two parts back under each other, remove the tubes and the plates and then open the cubicle, from which a smiling assistant appears.