A test-bench vice to hold circuit boards or components in place while testing or soldering provides a convenient third hand for getting your work done. When you're in a situation where a test-bench vice is not convenient try using a big wad of Play-Doh as a substitute vice.
Having a 3" round wad of Play-Doh in my tool chest, placed in a sealed ziplock bag when not used, makes a quick and useful substitute for a third-hand.
Play-Doh stays "workable" and circuit boards or components can be inserted within the ball in any fashion suitable to hold them in place while testing or soldering. When finished, place the Play-Doh back in the ziplock bag and it's ready for use again. It's really handy!
You can also get a great third hand from Jameco here.
If you have an electronics story or project you'd like to share, please email MyStory@Jameco.com