Guess the Mystery Project!

So I have my equivalent of the skunk works going here at home and have a couple of secret projects I'm slowly working through (in between finishing up that castable 39(H) OP, which is actually fairly close now!).  Rather than simply spill the beans and say "hey - this is what I'm working on" - I figured it would be more fun to do  a slow reveal on the project.  So here are a couple of pictures of the plans and the initial pieces of styrene sheet cut to shape. 

 

 

If anyone can guess it from this, I'll eat my hat, but as time goes by I'll post more photos.  I don't think it'll take too long once the hull starts coming together for people to get this one!