Draw a magic bucket

Stick a piece of paper under the transparent disposable cups and cut off the excess paper. Take the same piece of paper, bigger. During the performance, (the cup is facing down so that the audience can't see the paper stuck on it) borrow a handkerchief and a coin from the audience to cover the cup. Cover the cup with a handkerchief first, then cover the cup on the coin, cast some spells and take the handkerchief away. Of course, coins are invisible. Cast another spell and take away the cup covered with a handkerchief, and of course the coin will be seen again. Put away the cups and handkerchiefs, and it's over.

Well, it should be ok!