Your best bet is to locate a water damaged system which has an unblemished body. Then strip it down and swap out your working parts into it.
While this is possible it does have risks! First are you skilled enough to do this? Are the parts you can't replace still working?
This is not something I would attempt if you've never worked on MacBooks. You may end up just making a big costly mess!
As an alternative why don't you look at getting body covers. Many look dam good! We apply an adhesive version which has our graphics & logo (less likely to be stolen).