James takes model aeroplanes to a new level when he tries to make a full-size Spitfire out of Airfix. The venture soon hits problems when it becomes clear the giant 36-foot pieces may not be strong enough, and nobody knows how they will fit together. James hopes he can enthuse a group of reluctant teenagers to help him pull it off - but he soon realises he has another big battle on his hands convincing them it is a hobby to be proud of.
James tries to make a garden entirely out of Plasticine and then enter it at the Chelsea Flower Show. He persuades thousands of members of the British public to help make the thousands of Plasticine flowers he needs, but will it be enough to persuade the guardians of the world's most prestigious horticultural event to let him make a garden with no real flowers in it? While visiting celebrities like Stephen Fry and Joanna Lumley are clearly impressed with James's creation, the RHS judges take a dimmer view, forcing James to defy tradition and take matters into his own hands.
James joins forces with Edwina Currie to build a full-size bridge from nothing but Meccano. Top engineers pitch incredible designs, but the project soon careers out of control when the Meccano does not arrive and James realises it will take longer to build than he imagined. A last-minute accident also means that James's bridge may never see the light of day.
James attempts to build the world's first full-size house made entirely out of Lego bricks. With thousands of people and over three million Lego bricks, James attempts to do what no-one has ever managed, to build a two-storey house using this colourful toy. Such an ambitious undertaking is not without its problems and James soon has issues with planning regulations, an interior designer who can't get her Lego furniture to stay in one piece and a structural engineer who tries desperately to stop everything from coming crashing down.