What are some of your favorite mechanical devices?

I have a great fondness for simple, modest mechanical devices that we take for granted.

I especially like desky things, such as staplers, scissors, and hole punches. In the kitchen, it’s things like can openers and flour sifters.

For purposes of this question, a device is a tool with moving parts that require an operator.
Ballpoint pen: yes, pencil: no.
Tongs: yes, fork: no.
Clippers: yes, hatchet: no.