tin,
I don’t know if you can still find them, but back in the day when I was an uncouth savage still using a physical board and playing pieces, there were companies that sold plastic unit sets similar to Axis and Allies. (The color was slightly off, the models unperceptively different, just enough so they did not violate copywrite or something, maybe they were inept but had license to do it.)
Anyway, that’s how I got “half-battleship” pieces. (What you would call Cruisers today.) Also got some destroyers this way too, though, it was hard to tell them apart from submarines, so we had to use control markers to help differentiate. (Hey, a bottle of vodka will skew anyone’s perspective of the board!)