I've seen many engraved by hand using an electric engraving tool (Sears has them), hand-stamped (letter by letter), or for the professional look, take it over to your local trophy shop.
On our VAF dataplate, I had the trophy shop add this in the center, below the VAF logo:
SoCAL Wing
Lancaster, CA

Rosie
__________________
Paul A. "Rosie" Rosales
Rosamond Skypark (L00), CA
RV-6A, 4200+ hours since 7/4/2000