In its traditional setting, this was a sideshow illusion. The host would introduce the prop by opening the front and the top and showing it completely empty and ungimmicked. (Which it is!)
The girl is introduced and she enters and is hypnotized as the top and sides are folded back into position. He explains that he will make her disappear and he reaches down inside and removes her costume to prove that is all that's left of his beautiful assistant.
To further prove his point he will insert razor sharp blades throughout. Blades are inserted from every angle making it virtually impossible for anyone to still be contained within the cabinet. She has truly vanished.
The sideshow magician would go on and tell his audience that she is really contained within the cabinet...that it is an old trick...and that he would be more than happy to show how it's done for only X-amount, "and don't let the nudity bother you."
However, this has also been performed for many years as a straight illusion with the girl going in the box, the insertion of many blades and her reappearance.
