you could buy some Wrap from here (brand i used to make my stripes and i used the metallic black).
https://www.metrorestyling.com/3M-10...p-s/101893.htm Ask a shop if you buy it can they cut it for you? I would also ask what brand they use and use that brand. Since they will use a computerized machine to cut it. Unless if metallic is thicker but i dont think it is. I dont think you will find anything that will match factory metallic black perfect though. Avery brand i think has a wrap called metallic milky way and its SUPER metallic.