Yes, you can find small bits . But that's not going to turn your wood router into a precision mill. While the larger bits used for wood are tolerant of a little runout, the tiny ones used for metal, where the runout of your spindle is a much greater percentage of their diameter, will snap. Holding onto the stock is another problem; small pieces of sheet metal are hard to hold down, and tend to rise up and break cutters, which are quite expensive in small sizes:
FRAISA eShop - Fräswerkzeuge
If I had to do this job with a wood router, I'd cut the parts out in wax, which is more forgiving of errors, and send them off for casting.