Vacuum forming is a very simple technique that can produce thin-skinned parts of various forms. I mainly used vacuum-forming for producing the gun shields for the twin 4″ mounts and the hulls of all the boats and launches.
This is it, basically. A small box with a connection for your vacuum cleaner and a series of holes in its top plate. Try keeping the box airtight at the seems. This is my small version with the basic forms of several small hulls awaiting to be copied.
Part two is a small double frame holding a sheet of plastic. I used a few simple clamps to keep the plastic sheet firmly in place. As you need to heat this part, not using metal might be a good idea.
Heat your oven to some predetermined level, whatever works, and start heating the plastic sheet. Once the plastic gets warm, you’ll notice it will droop down. When you think the plastic is soft enough, fire up the vacuum cleaner, take the plastic from the oven, and thrown the sheet on the vacuum former. The plastic will nicely form around the moulds. This will take some practice and sometimes a mould tips over or the plastic won’t form properly over the mould (folding around edges). This is also the part where I should warm you that you can burn your fingers. I use large plastic sheets, not the more expensive styrene by Evergreen. When an attempt fails, I usually throw the sheet back in the oven and start again.
Here is a series of copies of hulls. You still need to trim all the parts to size. The reproducibility is as good as the moulds (they might suffer a bit) but this is a very easy technique to use.