well i have a 6 disc release at my hands - so either 6 custom single covers or may be 3 custaom 2 disc covers - anyways - i guess any nice motives taken from planes or even satelites showing nice nature vistas would be great as a front side motive ;) ....
btw. i still have not found any online shop in Europe that sells empty 4 disc bd covers (preferable by amps or similar quality), single and 2 disc covers are no problem now - since 2 months ago even 2 disc covers were unavailable at my sources ...

cheers - ahab