Summary
cut from 3mm ply wood. You will need two matchsticks. No glue required. The top section is held in place by the tension of both side panels. The front and aft rudder clamp everything into place. Just insert them through the respective holes in the side panels and push them down. The match sticks will hold the two outer small panels (the bulging things) in place. The picture is of the first attempt with just one match stick, so yours will differ ever so slightly. Surprisingly it floats upright and is therefore bathtub approved.
Open the files with inkscape and convert into desired format. The red lines are for cutting, everything in black is for decorational engraving.
