Claw
The bolts in this don't work because they are to weak but if you put in screws everything else works fine.
This was used for a Baxter robot controller http://wiki.lofarolabs.com/index.php/Baxter the fingers stay a constant distance from the hand like they are moving parallel. as with the Baxter hand
there is a part on the finger insert that needs to be broken off it helped the print so that it didn't need supports