And this the advantage of learning by doing, improving the speed and efficacy with which things can be manufactured. Here's the 6mm laminate, and I notice that if I score just one side without an incision that spans both, the material can be folded relatively intact and filleted with adhesive along the inside joint.
In fact you could go one further and arrange for all four sides to be foldable like an origami kit, with the three sides set as here and the fourth separately so prior to the addition of the two end-caps that support the assembly between the pontoons.
