After many failed attempts at vacuum forming different thicknesses of ABS plastic, I ended up building my own enclosure out of leftover sheets of 1/8". Basically I fused the front bezel of my GPS to a trapezoid-shaped panel with a window cut into it, and then boxed the whole thing out using ABS cement and a soldering iron. I removed the face plate from the CD player, and this enclosure screws directly to the metal bracket of the CD deck. Even though this partially blocks the center vents, I prefer this to losing the center vents completely. Once I clean up the interior some, I'll get some better shots of it. Right now it's just a GPS, but I'll be adding a backup camera soon.

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2003 530i, Silver on Grey, BC Coilovers, Square 9.5" M-Parallels, Gloss Black Roof
2007 328i, Alpine White on Black, Sport/Nav/Premium
SOLD: 2006 X5 4.8is, Lemans Blue on Black