I've done some very cool things, at very little cost, and saved time by making things out of other things. You might consider picking up some existing louvers, scoops, etc, that you can cut, bend, reshape, attach to each other, or modify in some other way to make something original. And think outside the box too. Old aircraft sometimes have some neat vents for example.
You put that perfect, it's all outside the box thinking!lol From a cheap libby hood I picked up on CL to all the other vents, louvers, few diff cowls from messed up hoods. Work has been nuts but I saw a hood on a CAR today that might look good with parts I want from it. As stated I have few ideas and one that i think is pretty good. Time will tell!