Just finished this galleon shipwreck:
I ordered an incomplete, used ghost pirate ship — set 4806 — on Ebay, a while ago ( $35 incl. shipping ), and went to town with a dremel, jewelers saw, and acrylic paint. Took about a week, in my spare time.
The acrylic paint held surprisingly well to the unprimed hull. I started with a black wash, which I applied with a couple brushes ( one 1/2 inch, and the other one, small, to re-emphasize select plank lines and cracks ), and then switched to an olive-green wash for the algae, applied via a torn sponge.
I finished by cementing eyelash yarn ( which I first sponged with the algae wash, to knock down the shininess ), followed by a few clusters of modelmaking clump-foliage. ...I could have gone with another layer of lighter, apple-green algae wash, here and there, but thought better not risk it; plus, the project's due (birthday).
Note: I was tempted, initially, to use a laser level to make a diagonal cut across the hull, so the ship would be more realistically tilted sideways, partially sunken into the sand, but thought better of it, as that would make standing figures on deck impossible ( in addition to likely hampering the swivel-deck feature ). This is meant as a playset for my nephew, after all.