SIPengineer, what you are describing is a completely different animal to what most of us here are used to dealing with, which is one-off, site-specific, building designs, or at least that is what I am used to dealing with, so take my comments with a grain of salt. This seems like something of a hybrid between building design and product design. The sheer volume of buildings/products being talked about is quite unheard of for typical structural engineers (160,000 pre-orders and 10,000's units per year). If I were in your shoes, I would be seeking out the council of my insurer and of a good attorney to help me structure some sort of compensation agreement that would be appropriate. I don't think a simple re-use fee is really applicable here. It might be, but a lot of thought would have to go into it to make sure to capture all of the variables at play. The stock option that you mention is interesting. I was thinking that some sort of equity transfer as compensation might be something to think about. The $80K-$120K per year amount might work as some sort of a retainer for general engineering, but I would not accept it as adequate compensation for your contribution toward a potential $9.6B in projected future revenue (160,000 pre-orders X $60,000 sale price = $9.6B). Call me crazy, but just to do the structural design for a prototype for all 50 states I would think something on the order of $250K might be reasonable as a starting point, but I would want additional compensation on top of that for the extremely high volume of projected units sold. Instead of a re-use fee, is this something akin to a royalty? Like I said, seek the advice of your insurer and a good lawyer.