Those are definitely some cool sub suggestions - and I already scratchbuilt myself a USS Halibut, Mike, but in 1/600 scale. And any kit would have to be very small as well; turns out that casting large pieces in resin gets you into a whole different level of industrial handling and storage of chemicals and the finished molds. Plus, the casting itself becomes tremendously more demanding - at the same time wiping out the ability to apply my special techniques which none of the competition has/does.
I can make parts for the big Renwals, etc., but won't be making entire hulls on that scale for quite some time (if ever).
So enjoy building those plastic kits with your little guy - definitely send us pics of his finished builds - and I also predict you're going to love the new little teeny parts I'm just about to come out with, buddy.