Custom Plating for amplifier faceplate......any possible problems

Copper shouldn't cause a problem. It is used as shielding inside some high end components. 

I know that pioneer and Sony made some times with copper plating on the chassis, as did ..uhmm..Denon. Counterpoint, as well.


Lots of companies did this. Some have issued faceplates that were copper. coated copper, mostly, to avoid the oxidation issue.
I think symphonic line did some copper ones.
https://www.audiogon.com/listings/lis9199c-symphonic-line-kraft-400-monoblocks-with-internal-stealth...

Ok, that is definitely good to know. 
If anyone has any other thoughts, please feel free to share. Thanks

Not only will it not be a problem, it will almost certainly be an improvement. Do it and listen. You will hear.

Do your own prep on the parts before sending to the plating company. And then "Still", Pay to have the plater go over them again before the process begins. Otherwise you have only about a 50/50 shot of not having problems. "If they do the final prep? And there was a problem anywhere in the process? "Like someone sneezed"? It happens!  They will just redo it". If they do not ? ANY off-marks or coloring at all will have you paying twice PLUS the extra prep work!
 Also, Either clear anodize OR use three coats minimum of a good polyurethane as a final topcoat.
Copper is very soft and scratches easily. The plating must have a spec. for depth also, "Give to the plating Co.". But, DO NOT, ask for a spec.. OR allow their,  "Shop tolerance spec."
"Otherwise the plating, "May" be so thin it rubs/wears off simply after cleaning several times! Especially with oxidation.
 "Brass", because of it's inherent properties may in fact be a better choice for you. And you can have the topcoat anodizing "Tinted", to give it some UV protection as well as a cool coloring shading. Look at "Red". 
Hee hee, NOT, "RED",  anodizing though". That would be atrocious!
 If you do go with clear anodizing in the topcoat you MUST spec that depth also. "In Microns". And always give the "Finish" in the scale that they use. "You can look at (Shop finish gauges), online to see what I am talking about. "I forget that particular scales name and rate system though....."
 You can ask your plater to show you
exactly what they use as, "Finish Gauges", and go from there. "This you can then pic, AT the plating shop". That's all they should need.
 If they look confused when you ask about anything I have mentioned here? Run. Let JoBob and Jr.Bob, make those x-mas ornaments while you find a real plating company.

Raw copper will oxidize to have a satin brown color. Unless you don't mind the color or polishing your face plate at intervals, bad idea but only from a cosmetic stand point. You could have it clear lacquered after plating I suppose or you could have it gold plated:)

Thank you all for your updates in helping me on this, when can I post a pic so that all of you can see this :) 
It turned out like a "million bucks". Thank you everyone and works just fine.

Sounds like a dumb idea.Good luck!!

Some of the vintage gear had copper faceplates and they looked awesome. Can you show a picture of the finished project?I made a set of Model 19 Altec crossovers for my Altec project, stand alone, made the control panel from 1/8" thick brushed brass. Looks fantastic.
BillWojo

Here you go!!

https://imgur.com/CI88MHZ

More:
https://imgur.com/NSjLvc8

https://imgur.com/NsiA5t1

That looks very classy in copper. You have to love the look! Great job.
BillWojo

Thank you!