Quote from their website:
Each kit is supplied in the form of flat brass sheets, etched with surface texture and fold lines. The parts are sized and shaped to assemble into a sturdy brass model, by means of folding the brass along the etched lines. There are 'tabs' at the corners to allow for the models to be glued together. Some modellers who are already adept at soldering could use that method too, though in all product testing I use glue. All the kits are supplied flat-packed and unpainted.