basically buy some copper clad polyimide and etch it with the same technique u use to etch a razor 0.o
copper clad polyimide is extremely hard to get but u can buy it off these dudes
http://www2.dupont.com/Pyralux/en_US/index.htmlu'll have to speak to their supplier rep dudes
i havent bought any of this yet but am hoping to in the future,just thought it'd share this