Some signs I made using plywood, Oracal 810 masking, shellac and rustoleum spray paint.
I sanded the board and applied shellac
Sanded and sprayed a coat of paint
Sanded and sprayed 2nd coat
Let dry and applied vinyl masking
Apply shellac to engraved wood
I have used the oramask 810 a few times and it has worked good. I used a 90 degree Diablo bit from HD