I've bought a pair of used fog lamps to experiment on. First, I cracked the plastic bracket. Then I cracked the transparent plastic when trying to split them - they were corroded, but apparently not sufficiently to be split despite bathing in WD40. I think I'll end up buying a new set from the stealers and watch the warranty.
Now I know it's official: my manual skills are limited to opening champagne and unfastening bras.
By the way, I've noticed that most old sets were made by AL Automotive Lighting (assembled in Mexico), and the new replacements are made by Bosch.
Another idea.
There are OEM fog light covers that fill the holes, originally meant for facelift E86 without fogs.
51 11 7 158 835
51 11 7 158 836
http://www.bmwstore.pl/pl/katalog/diagram/51_5929-obudowa-zderzaka-przedniego/vLZ31262#part03
Photo: http://realoem.com/bmw/showphoto.do?id=51117158835
Excellent material for fitting proper DRLs.
Perhaps I'll buy a set and screw Philips DRLs onto them. The total cost (2 covers, a small Philips DRL set) will be about the cost of one fishtank from the stealers.
EDIT:
bought the blank covers
bought OSRAM DRLs - the Light@Day model, which does not rely on chavvy spots of light but on the light guide technology.
Had the covers cut to measure and the DRLs wired by a local indy.
The final effect:
More:
http://www.z4-forum.com/forum/viewtopic.php?f=2&t=42079&start=15