We decided to exclude the traditional list of "simple machines, " which includes the lever, pulley, wheel and wedge, since most other tools employ some form of simple machine--a hammer is basically a lever, and an axe is essentially a wedge.
After all, the piano is such a welter of machinery: Push a key and before you hear a note, a small lever pushes against an intermediate lever, which pushes a jack, which pushes a roller, which pushes a hammer toward the strings.