Over at Street Tech, BB buddy (and old-school bOING bOING contributing editor) Gareth Branwyn explains how to build this beautiful twin-enginer solar-powered robot that rolls around on a pair of hard disk platters. The robot was designed by Zach DeBord who exhibits his elegant mechanical creations here on Flickr. DeBord's bots were all built using a design approach called BEAM (Biology, Electronic