Every third hand I have ever used has been really terrible. I've heard that coolant tubes (used in machining) make great third hands (they don't move around once you place them, and you can place them anywhere, at any angle, in 3D space).
I looked online, and sparkfun (who I love), sells a third hand that takes advantage of this (yay!), but theirs is just a rectangular plate with some threads in it.
We can definitely do better!
Today I'll show you my version of a third hand. It was made as a gift for a good friend of mine (sidenote: flate rate shipping boxes from USPS are awesome! This thing ended up weighing a TON, but it was still cheap to mail it halfway across the country).
The "body" of the 3rd hand here came from some remnant stock I picked up at my local metal supplier (been sitting on the scrap shelf in the lab for at least a year now), and the head and legs (bolts and nut) came from a really awesome scrap yard in Phoenix called Davis Salvage (the only place I know of in town that still lets people dig through scrap).
I built this at Heatsync Labs in Mesa, AZ. If you want to come there and build something like this with us, come over! We have open hours almost every day of the week! (come in and use the lab: as always, it's free).
Step 1: Gather your materials
Here you can see the base materials that I'm going to work with layed out here. Not pictured are: the alligator clips I used for the "hands", and a heatsink that I cut in half for the mohawk!