I'm not sure what to do really, so I've started off with a wood thing. I was thinking adding a bit of rope here and there and maybe some metal linings would be cool. I'm not sure how interesting you can make a trebuchet.
On a side note- I forgot about Megacon. I hope i'll be able to finish this :\
Edit: Well, I figured I might as well post and say that I did indeed get the color and alpha maps finished. I'm new to 3d studio max though and could'nt quite figure out how you link a specular map :\
http://www.youtube.com/watch?v=INpbN98yplI