Main ingredient found at home depot: spring loaded toggle bolts(3 different sizes). I used 14 of these total, to form the fingers(metacarpals) having the same number of bending knuckles/joints that human fingers have. You may spend 10-15 bucks on these.
Everything else in the build is made up of old computer,printer, and other random electronic scraps. Use what ever you can slap together and form the frame/hand/arm, depending on how big you want to go with it.
I fabricated the fingers first, attaching the toggle bolts together using small machine screws (pre drilled holes) and hot glue. Connecting the toggle bolts from large to small gives it a more realistic look and helps the fingers to not have such a sharp curve.
I then cut small strips of metal (folded two sides 90 degrees for rigidity) to create the carpals. Then attached the fingers made from the toggle bolts to the carpals then cross-braced the carpals with more metal to hold them all together.
The thumb was a little tricky, hopefully my photos help anyone who wants to attempt a build like this. As you can see, I kind of just built mine as I went, using whatever pieces parts of old electronic junk I could find. Once I built the entire hand/wrist and added enough bits and bobz to give it character, I wrapped the metacarpals with a strand of wire, giving me something to lace the string (tendon)through that actuates the fingers. When you pull the string, the finger will bend closed, when you release, the springs in the toggle bolts will retract the fingers back open.
I wish I could give better instruction, but I mostly just let it tell me how to build it, as I built it. Probably would be impossible to duplicate it exactly, guess that makes it pretty unique. Of course there are simpler ways to achieve an articulating hand using rubber tubing and what not, but if you put some time and imagination into it, you can have an awesome looking robotic hand/arm with fingers that have 3 articulating joints per finger, just like real fangas. Snap yo fangas.