A palanquin is brought onto the stage, with four bearers, with an assistant reclining on it. The curtains are drawn and after a slight pause re-opened: the assistant has disappeared. The bearers stop briefly, so that the effect can be seen, then proceed off-stage.
The four posts of the palanquin are hollow: the platform on which the assistant reclines is not actually attached to the frame, but lies on the real bottom piece. Ropes go from the moveable platform, though the posts, around pulleys at the top, to counterweights concealed in the canopy. When the curtains are drawn, the bearers release the counterweights, which hoist the assistant up to the canopy. She, or he, is a slight person and lies so as to take up as little space as possible.
The posts need to be bulky enough to support the weight of the platform and assistant, and to hide the weights as they move and as they rest on the bottom of the palanquin. The curtains will assist in hiding the weights. It will have to be decided who pulls and opens the curtains, and whether there is one release or four. The palanquin can be made to look much lighter than it is by judicious use of paint to indicate shadows or to minimize the apparent size of the construction. Obviously the bearers have to be hefty enough to carry the thing without strain and to conceal the shift in weight as the assistant is hoisted up into the canopy.
As it can't be repeated or reversed easily, this is a good trick to cover a slight pause in the performance for instance if something is being set up or if the performer is magically waiting for something else to finish. Or, perhaps, the performer spies the assistant, yells "You're supposed to be backstage getting ready!", and disappears her or him!