I started with this piece cause it looked simpler than the cabin air filter housing, but, man, was I wrong. Essentially no surface on it is flat, except for the one that butts up against the firewall. Took me a really long time to figure out how to approach all of the curves.
Yes, I realize that a lot of the geometry is there for mold release, but I want to make something that fits all E46s, so I decided to spend the extra time and recreate it as closely as possible. More time spent in CAD land saves me from redesigning the piece down the road if it turns out to not fit on some other chassis configuration.
I also decided to not model the front clip retainer into the piece. I like the idea of using the stock injection molded piece for serviceability. BMW does not sell these separately, so I'm gonna have to go junkyard diving for some. Fortunately, they're just plastic welded in, so they're easy to pop out with a razor blade. This part could also conceivably be recreated, but printing it in a favorable orientation might be tricky.
Also, did some preliminary slicing of the model and the printed version should weigh in at 300-400 g, depending on my choice of material and infill. For comparison, the stock piece weighs in at 1618 g. I do need to split it up into three pieces to fit in my printer, so I'll add some features to bond all of them together nicely. For now, I just added some slicer-generated dowel connectors:
With the stock geometry recreated, I can work on modifying it to accommodate both the braces and the tilted filter. Got some ideas flying around in my mind already for how to approach that. More to come.
Sidenote, since I essentially made a 1:1 replica of the piece, anyone can print it out without modification and save ~1.2 kg. Who's up to be the test fit guinea pig? Hit me up and I'll send you the stl (I'll distribute widely once fitment is validated).
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