The architect travels to Macclesfield to meet a first-time builder who hopes to transform an allotment shed into a Doctor Who-esque, multi-functional play den for less than £300. He also visits a spectacular live-in tree house in Scotland, and creates a medieval-style lock for the wood cabin, with Will's help. The Italian road trip takes in a holiday lodge made almost entirely from glass in the Dolomites (subtitles)