It's amazing to me just how creative my 2.5 year old son, Tre, can be when left to his own devices. I've seen him figure out that a Pringles chips container lid fits the smokestack of his toy train perfectly (something I wouldn't have even thought to try). I've also watched him figure out which of his magnetic letters will hold an M&M and which won't (hint: it frequently depends on the angle you hold the letter).
And as I just a moment ago glanced at him playing quietly next to me, he has an office chair lying on it's side, a fly swatter stuck into the center post between the wheels, and he's talking on the plastic swatter end, occassionaly "dialing" someone else by poking at the plastic.
Isn't it amazing what a child can think to do when not told they're not supposed to?