Hooray! My first thread.

I was wondering if anybody had any tips or ideas regarding the modification and/or use of household items as toys? Something small and easily concealed from housemates, (i.e. no full suspension frames, heh heh) and something that doesn't take an industrial machine shop to make. The more original and clever the better! Also, being a university student, the ol' budget is a little tight, so any ideas would preferably be relatively inexpensive.

*rubs hands in anticipation*