I called the California State Board this afternoon. The code enforcement person I spoke with didn't see any issues with essentially a "giant seal" as long as it is not used on plans and used for display only. But they probably don't care about a kid who may sell a handful of these haha.
Can you accommodate an 11x14 license? Is it only for the state of California?
I am only licensed in California, but I can try to recreate a seal for another state. I checked the dimensions of an 11"x14" rectangle in an 18" diameter circle in CAD (something about a square peg and round hole comes to mind), and it barely fits, but doesn't allow for space around the certificate for the standoffs. I was limited in size for the round portion to 24"x18" (limitations of equipment), but there is nothing saying it couldn't be built in two pieces.
I just checked in CAD too, it only leaves 1/8" from the edge of the rectangle to the edge of the piece of wood. So really tight. I forgot to say yours looks AWESOME! very nice job!
I could do it in two pieces and then glue it together. The Oregon stamp would lend itself well, since the it looks like it can be cut in half. Scaling it up in CAD, I came up with ~22" in diameter.
Roundabout way of answering... Yes, I think I could accommodate an 11x14.