Didn't you know, lawyers are outlaws, they're untouchable and will steal every penny you have, weather or not you win or lose?! That's why if you ever wanted to get into kit building, you better be good a designing or know the person who designed the plane and ask to use his design and pay the royalty. Then your in the clear, now-a-days, all the major players have to do is say, "hey, don't we make a cessna like that?" and the next thing you know, they're pouring hot sauce on your back side while bending you over. They don't own the patent for the cessna plane, your's just looks similar. You would have to design something that looks like it's a tank inorder for the major players to say, "nope we've never made a flying tank, Oh wait, what about our duraplane!?"