maybe apply a tiny coat of superglue in the scratches but don't use you finger to smooth it out,other than that the only thing I could think of is a plastic filler from a hobby shop.
Just call them character marks, battle scars, make up a big story about how you saved a small kitten from a burning building using the the laptop as a block to gain extra height, enabling you to reach the second story window.
Really I have no ideas, sorry
BTW: Welcome To TechIMO
__________________
The impossible takes more time,and costs more money.
hardware
prices 
Are you talking about the outer plastic case?
