I use a 3x17 round cake pan. Cut the bottom out and riveted to a 1 1/2" drop base open filter bottom. I had some extra window channel rubber to seal to the hood. K&N 14x4 and summit filter top. I have a 16" round hole in my hood and use a dual snorkel scoop.
Thanks! thats some good info for a cheap base plate. I'm going to need some kind of foam to seal to a non flat hood. If this workout and i like it. then i will hack a hole in my nice flat hood and attach a scoop of some sort.