Hi,
in order to make things look as OEM as possible in my current 850R RN-swap build, I thought about how to make the 540i MAF housing fit as nicely as possible to the stock airbox cover. I'd like to show off my first little project for the car 
.
Required:
- 540i MAF housing
- P80 airbox cover (from S/V/C70) as it provides a bigger surface to work with
- Dremel or similar
- 3D printer
- ABS filament, black (durable even at temperatures up to 100°C)
- glue to stick housing and adapter together (need glue which works with PP plastic)
Result:
Preparation:
https://www.dropbox.com/s/libp5z81hb86k8l/IMG_3634.JPG?dl=0
Adapter:
https://www.dropbox.com/s/rx7lrszr8b8esbd/IMG_3635.JPG?dl=0
End result:
https://www.dropbox.com/s/a5i9woe6zkf4sd4/IMG_20150119_100227.jpg?dl=0
On the picture you can see the glue and scratches and so on. this is not visible in the vehicle anymore unless someone looks really closely.
The MAF is a very tight fit in the adapter but to be sure we added holes for screws which can go through the slots at the side of the MAF housing. I even have a fitting o-ring.
Looking forward to test it in a running vehicle but it should be fine. Maybe the stock airbox is too restrictive after all for serious power, but I will try it out. For TD04HLs it should be more than enough though.
3D printing is a very nice technology and this is just one example of what you can do with it. It's also great for custom brackets and all kinds of things. With ABS filaments the thermal resistance is also high enough for most applications.