What sub to build
Dive systems 1&2
all particularly useful. The photograph sections give you an idea of what subs already exist out there. (And also what does not exist - if you want a rather unique sub model)
There is not much information on there about some increasingly common routes into the hobby:
- purchasing a hull and fitting it out
- purchasing a complete kit
- modifying a plastic kit
- refurbishing a submarine bought on eBay etc.
For these you will need to look on the Forum or on other sites. "Build logs" are particularly useful.