Well, finally .. someone decided to make their own CAI. I know that they do not do much in terms of performance but I decided to make my own as well. Are you planning to use plastic or metal? I am using metal because my brother borrowed his friends welder. I started yesterday and this is what I have come up with until I have more free time to work on it.
You can get your filter damn near anywhere .. but I would go with a K&N if I were you. Go to their website and you can look at tons of sizes, shapes, dimensions, styles, etc ... Give me some ideas that you have too .. For instance, I need to figure out where to buy nipples for the hoses. Or if there is another way ...
FWIW: I have successfully made one for my truck and people constantly as me "where did you buy that from" .. I respond, I made it in my garage. The look that people give you makes it worth it if nothing else.