We have a chrome shop by our work that does stuff like that pretty cheap. A bumper might cost $300, but a case might not be that much.
They have to clean, etch, copper plate, and then Nickle plate. The copper is the expensive part. I had them stop at the copper step for a reservoir because it was sexy...and functional. Most folks what parts dipped 3 to 5 times in the shiny stuff where you can stop at one since it's just a computer and not open to weather.
The 690's plastic comes off and you're left with a shell on all sides. You can call a chrome shop and see what they recommend for masking. I just had to use some Vinyl 3M tape
on stuff I didn't want coated. They'll dip it in nasty stuff that'll eat off regular masking tape.