Giant 3D printers for making boats, bridges, buildings and rockets

BOAT BUILDING3D3D is a long-winded and tedious business, even when what is going down the slipway is a small craft made from modern materials such as fibreglass, rather than something nailed together out of planks of wood. Construct a mould. Build up layers of resin and glass fibre inside that mould. Extract the completed structure and finish it. All told, it can take months. That, though, may soon change. For researchers at the University of Maine are now in the process of testing an 8-metre (25-foot) patrol boat that took just 72 hours to make from scratch (see picture overleaf). Their trick was to build the vessel using a giant printer.Since they appeared in commercial form in the 1990s, printers have generally been employed in factories to make small things like prototype models, components of jet-engines and dental crowns. Now, a new generation of outsize printers is arriving. These are capable of turning out much bigger objects than previously possible, and printing them faster.