The assembly of longitudinal girder. The plans show 2x 12mm. plywood and around a wooden 40x40 beam. I do not like that solution so I made them of 6 cm Core Cell foam (4x15mm glued together), a glass fiber corner profile at the top and all around another six layers of 600gm knitted glassfibre. For the nuts on the engine mounts I made a fortified recess.
