Bitz and Bob's junk stall sells out of everything, including Bob's robo-helmet! Bob is horrified. The gang try all sorts of substitute helmets: Bitz's craft box, a traffic cone, even a knitted helmet. When they try making a helmet out of a piece of cardboard, it isn't quite right. But Bob accidentally squashes the craft box, and Bitz figures out they could use its flattened shape as a pattern by drawing round it, cutting it out and folding it in the same way. But Zip and Pop may have a surprise for Bob!