i have used a piece of a body clip before...i have used a nail before...i have used a stiff piece of mechanics wire...and I'm sure i have used a few other things...lol...anything that is the right size will work in a pinch...
I've always used a piece of hex wrench if I lost a pin, they are generally pretty strong and I have a lot of the hex wrenches in various sizes that have come pinion gears ect.