Been umming and ahhing over this. Its a sub so needs a rota.
Was thinking of scratchbuilding one from 1/48th helicopter blades, but this is a cheap and cheerful build and don't want to go to too much of an effort on something that'll most probably end up a silly whimsy.
I first thought i'd do away with the original rotor and fins, thinking they're too cartoony. So i've bunged some primer on to see what happens. Hmmmm... might use it.