I have started making the diving helmet in Hong Kong, and finished it in Glasgow. It is based on real diving helmets from early 20th century. The form is made of EVA foam, the details are various materials including laser-cut acrylic and plywood, light resin casts of wing nuts, resin and latex casts of barnacles and 3D printed parts. The idea was to make the helmet look like it's spent a lot of time under water or washed out on the shore, hence the barnacles; there's also water trapped behind the front and side visor glass, so the person wearing it looks as if their head is submerged under water. The air circulation is allowed by top visor, which has no glass, and through the system of holes disguised in some barnacles.
It's been a great project to make!