I was rolling through my CAD portfolio site and came across these. I know a couple folks here have done some interesting ITB/custom plenum things. I dunno, here is a little something to get some ideas out there.
Idea 1: My first idea for one...the early days of my CADing.




Idea 2: A little more CAD experience and fuel injector idea from Ferrari F1 motor
See the attachment at the bottom for a little artistic license I took with it. The heat shield was more or less real. I made one from aluminum sheet and made a CAD version of it after. I even made a wood mold & bought a vacuum pump so I could bag a CF one (had the fabric & marine epoxy). I just never got around to it, and am sticking with the OE filterbox on my 2nd M42.





I still have the model for the injectors if anyone wants a copy. They were made from measurements I took from real ones. Lemme know what format you want them in and I will do what I can. STEP is probably the easiest, and I use IronCAD anyway so the feature data would be lost in any translation.
There is a bunch more stuff over there too:
http://prof.e30tuner.com/I have models I made for custom coil-overs, custom AL flywheel and an exploded I4 engine. The engine model...it is a veritable Where's Waldo of "find the mistakes in the design." I sorta did it off the top of my head when I was 19 in my spare time one week. I keep meaning to do it again, for real. I have a thread for that too lol.