gripping mechanism in a robot

[Piyush Goel]

I'm an undergraduate student of 3rd year,in Electronics and Communication,i want to build a line following robot which will be able to pick light objects.i want to build a robot somewhat like this

No Man's Land iNexus(2011-12) Team 1828 Nagpur.wmv

and need help with the gripper.
i've worked upon Atmega8,recently participated in the wall following competition at iit bombay techfest.