here ya go man…
took me forever to find this as the metric is not native here. Thats going to be a real bitch to do though since the holes are already so big. Generally have to drill a 10mm pilot hole in the CP for the post on the hole punch to fit through and properly align the holes. Maybe if you put some spacers or a piece of wood with a pilot hole in there it would be sturdy enough to support the die cutter. Good luck man, was hard enough with the 10mm hole. Depending on how many you need you might consider buying 2 of them. By the time I got to the 4th and 5th button it was getting dull real fast, the 6th button I did not think would make it.
Either that or take it to a metal fab shop and offer the guys some pocket cash to do it real quick for you.