I have aquired a number of 12" and a few 14" iBook shell pieces (more tops than bottoms).
Most of them are very scratched up or worse... however, I was thinking about covering them with an auto/motorcycle vinyl adhesive layer.
Black and White carbon fiber are available options... or plain black... and I have even seen vinyl used for home decorating in silver and granite/marble/etc...
let me know if you might be interested in purchasing on.
I'd need to charge about $20 plus shipping per piece to recover supply costs. Or, you could just buy the really beaten up case pieces for $8 plus shipping each.