Its sort of a 'wishes were horses we all would ride' kind of thing.
In order to build a suitable model you need a set of viable plans.
I've worked with Jon Warneke of ISW in the US Archives (NARA) looking through the stacks for old battleship/cruiser/destroyer/etc. plans. There is a lot of old stuff which is untouchable, even by the NARA staff. Many are on an old parchament-type paper which were rolled and left. They are so brittle that they cannot be touched for fear that they will crumble. These items are being left as is/where is until NARA comes up with some new technology that will allow the retreival of the information contained.
Once you get a set of plans they need to be scaled to the appropriate size (FedEX/Kinkos to the rescue) and multiple copies made.
Next take the hull elevation and cross sections and laminate them to pieces of plastic stock. Cement all the butt line sections tot the elevation at the correct spacing. Brace as required. Cover the whole thing in masking tape and pour liquid resin into all the spaces. When the resin is hard, remove the tape and sand the resin back to the plastic forms. Fill imperfections, sand, prime, polish, repeat until smooth and satisfied with the form.
Apply applique items to the hull, rubrails, bilge keels, grooved deck, hawse lips, etc.
Build superstructure parts from plexiglass sheathed in styrene. Drill portholes where plans indicate. Add PE details to the master (hatches, hoses, etc.). Glue O1 level superstructure to the deck. Build subsequent levels in a manner that they can be cast.
Add other deck fittings. Make master pieces if you don't have some in your stock.
Now you are ready to begin production. Make a box large enough to hold the hull. Mount the hull on some pour stubs & cement in box. Box needs to be 1" or more larger in all dimensions than hull. Mix & pour RTV, degas and allow to harden. (BTW RTV costs about 30 dollars per quart (over the counter, bulk buys are less) and a large kit may take 5 quarts ! (Ca-ching $)
Make smaller molds for all the small parts.
Remove the master plug from the RTV mold. Did it come out without tearing the mold - good! If not, re-engineer and try another mold (Ca-ching $)
Mix and pour resin into the hull mold. A large battleship mold may take 4 or 5 pounds of resin. Resin also costs about 30 bucks over the counter. (Ca-ching $)
Remove the hull from the RTV. Quality time - did it pour & fill all the voids? is it useable? If not - re-engineer, repour RTV, repour resin, repeat (Ca-ching $).
Production - pour hulls and parts. Those which pass initial quality levels go into production. Those which fail go into the trash. Resin cannot be remelted and reused.
Due to the heat generated by resin as it hardens, the life of a RTV mold is 30 to 50 pulls (maximum). They may be less. In the initial production of the ISW USS Langley, the mold failed after 4 pulls. The master had to be re-engineered and new RTV poured. I have one of the first four kits made because I have the original configuration.
Make new RTV molds if your production run is more than 30 to 50.
Make all your small resin parts using the same steps.
Draw the photo-etch art. Deliver it to a etcher. Get trial sample back and verify that it fits. Adjust the art as required. Put the art into production.
Instructions .... well, ISW really doesn't do those well. Line drawings, exploded views, etc. Draw them up and print them out.
Decals -- send art out to a commercial shop. Verify and put into production.
Package - Box it up. Bubble wrap & foam peanuts for the hull. Small parts in a box or ziplock bag. PE, decals, brass wire, instructions.
Price it a a point which covers your costs.
This is all done by one or two guys in their basement (I've been in Jon Warneke's basement - masters, RTV, and small parts everywhere!)
How come a resin kit costs so much .... ?