You've obviously never worked in set design though. Set design: if it's cheap and looks the way we want it to look, that's GREAT!
Seriously, mounting on black is easy, therefore cheap. What you want is incredibly hard, therefore expensive.
I've been around set design and graphic arts for a long time, Haf. Mounting it on black will not look good, because you'll be able to see the black behind it. I don't want that. I want the roundel to mount on the front of a podium; it would look terrible with a square black border overlapping the edges. Put the idea of mounting it on black out of your head. It's not going to happen.
Cutting a perfect circle is not hard, at least in the sense of being difficult, it just takes specialized equipment. I don't know anyone who has access to that equipment, and I am unwilling to pay an exorbitant sum of money for what will amount to five minutes of work. So, bottom line, the roundel in RL ain't gonna happen.