For those that don’t know, the Jamming Gripper is a balloon filled with coffee grounds attached to a vaccum pump, the pump sucks in the air and causes the system to “grip” stuff. It is very effective. The link below provides directions on how to build a cheap version of this for your own robot projects.
http://carlitoscontraptions.com/2011/05/diy-universal-jamming-gripper-2-0/