For me, the thumb tip is a container. A container that transports stuff from one place to another. But with a big difference: the container is invisible! Both before and after the transport.
If we examine the usual procedure, we will note the system behind: when a silk is poked into the fist (thumb tip), and then vanished, it is ‘transported’ with the container from one hand to the other. Because the container is invisible, the object is it as well, and the audience should see or suspect nothing.
If you think of the thumb tip as a container, you will realise what amazing stuff you can do with it. Most important, you will hopefully cancel out your prejudices that the thumb tip belongs only onto the thumb!
Important is how to introduce and out-troduce this container. There are a lot of variations on this and multiple ruses that can be used. Because the thumb tip when worn is close to invisible, this task is made easier for us. Once in play, it renders invisible until it is secretly discarded.