DanRoM had some made up for the Ringmeet 2 years ago.
I don't know if he'd be able to get more but it's a standard plate holder with a nice FG sticker on it, so I guess it wouldn't be too difficult to get stickers reproduced if that's easier and source frames locally yourselves.
Tiny stickers would work really well. I have plastic covers over my plates, but there is enough of a black frame around the outside that I could fit small stickers on there.
Eh? I'm sure I had those and mine are both stickers. I think. Maybe it's just shiny plastic with it printed on, apologies if I'm talking out of my rear.