I was looking around for inexpensive solutions for data plates online and it occurred to me that GI-style stainless steel dog tags might work since an E-AB need only include the name of the builder, model and serial number. I can't find any specific size requirement for the plate or the text in the regs, just "firepoof" and "secured" and "legible," but the dog tags are a bit too small and the lines are too short if you have a long name.
Then I stumbled across the site below that sells dog tags and also offers "industrial nameplates" about 3-3/8" x 2-1/8" in .016" stainless with attachment holes in the corners and room for up to ten lines of text with 30 characters per line. The cost is just $14 including postage. Here's a sample a whipped up on their site:
I have no connection to the site, just thought I'd share.