Nothing simpler than a springer...

http://www.rcuniverse.com/forum/m_8861486/tm.htm

And I have seen springer hulls built out of wood, plastic, fiberglass, and aluminium.
It's such a simple box hull, practically any and all media will work.
The square lines are perfect for rescues.

[8D]

Plans are widely posted, around the world, on the internet.

http://nwrcsm.freeyellow.com/springer.PDF