This is a kit for an Astromech Gripper assembly. It contains all but the piston rods that can be printed separately in metal if you want (link). It's a funtional kit and you will need some hardware to complete it. First you need a pair hex head 4-40 screws 3/4" lenght and 2 4-40 nuts. You also need two 1/8" dowel pins 3/4" long to hold the pistons in place. Finaly the geared DC motor like this one: https://www.servocity.com/html/270_rpm_micro_gearmotorblocks.html#.VuCxn_l96Cg
Note: I added an extra worm gear so you can replace it. Designed in collaboration with J. McShan.