Now I've a 3 series beemer, and looking at the trip computer and other bits in my centre console, they are Black ABS with a sort of random ridginf effect. Now I've seen flight cases for harddrives which use the same material. or a green first aid box in Halfords. So I am looking to fins a black first aid box with no writing, currently looking in all the stores I go in for something similar, amybe those cases which tools come in or something. If I find something will update you.
WHSmith do 2 filing trays with risers for £5.99. Black plastic with that random ridging effect. bought myself and will try to hack them about to see what I can come up with. They are big enough to get at least 2 x double din covers out each, so I have four attempts to get it right