[Abathar]

The best way to do multi-directional windings is hundreds of years old.

I have made sand molds where they subject sand with a binder in a high pressure press around a steel support. In fact the shape is almost identical to this sub, just much smaller. Aside from the two small holes at the ends where the support extends out of the sand the mandrel is 100% exposed and there is no limit to how you want to wrap it before the vacuum bag goes on and into the autoclave.

When it’s done it’s just a matter of pushing out the center bar, cutting the end a little bigger and vibrating the sand free and out.

[rdcbn1]

Wash out mandrels and a fully composite vessel would have been stronger but the ability to put penetrations for access hatches and view ports would not have been strong enough or leak free - hence the titanium end closures.