Portals

You are a brilliant physicist who has been working on a side project at home for quite a while. At last, success! You can create spatial portals that allow objects to cross through one and come out the other no matter how far apart they are! You can also polarize them, so that solid objects can go in either direction, but light and sound go only in one. The size of the portals can be changed while they are active, although changing the size of one will necessarily change the size of its partner. The portals have only one active side each, but the inactive side, as well as the edges, allow them to stay wherever they are placed, whether it be on walls, ceilings, or human flesh. Your mind is reeling with the possibilities...