First off, that looks great brilliant work, many hours spent there like your other projects. You should do a book on these projects with drawing as I...
I use my lathe X axis the other way around, so it takes of diameter as you wind it in. This way you can take a clean up pass, measure it and put that...
After your tank you need to make up an oil skimmer, it's just a piece of perspex round disk that is powered by a low rpm motor and have a wiper each...