A bit expensive; something you won't see on mass-produced amps (except as cheap plastic).
"Looking for Custom Made Car Club Plaques?"
http://www.obrientruckers.com/ecom/product/252/2679/#5

O'Brian claims to be the world's largest producer of club plaques.
Traditional small-shop sand-cast Aluminum (also Bronze).
Sand-cast has texture.... it is traditional to paint the casting then belt-sand the high spots.
He's got stock items at fair prices if you want to see and fondle one.
Custom prices:
Belt Buckle Orders Up to 3" x4"
One Time Set Up Charge $75
Price per Buckle $20
Minimum order 10
Solid Bronze or Polished Aluminum
Shipping (per order) $10
Key Chain Orders Up to 2" x 4"
One Time Set Up Charge $50
Price per Key Chain $3.00
Minimum order 25
Shipping (per order) $10
(under $6 each for two dozen... if you build and sell more than a few amps, not a bad price for serious trim.)
Plaques and Toppers Up to 5" x 9"
1-9 $40 each
10-24 $21 each
25-49 $18 each
50+ $16 each
(also Up to 6" x 12"- $45-$20)
("Topper" could be a small hefty face-plate?)
"Artworks need to be pure Black and White
Black represents Raised (full 1/4" thickness)
White Represents Recessed (less than full 1/4" thickness)
No shading, grayscale, half tones or colors
Xeroxing a color drawing makes a grayscale - not a B & W artwork
Minimum spacing should be 2 Points or .028 inches
Try to keep you design simple so it can be read from a distance
If you want a horizontal plaque dont send us a vertical artwork
Castings do not have to be rectangular
Our main software for artworks is Corel Draw
We can import .jpg, .ai, .eps, .PDF, and many other files
Do not send us tiny 14KB files - they do not scale up
Save file as high resolution (300DPI or better - bigger IS better"