I'm leading a LEGO Mindstorms workshop for middle-schoolers in July 2011 and wanted to incorporate this Robot Arm project. The problem is the kits we'll be using don't have the claw parts listed in steps 16 and 17, so I needed a replacement that could be built with the parts we *did* have. Specifically, we're using the LEGO# 9797 kits ("Mindstorms Education") and must be able to build the stock arm plus the alternate claw.
This is a PDF of visual instructions for building such a claw. It can pick up the colored balls supplied with the kit, so I figure that's good enough!