Flex PCB Material - Pyralux - 6" by 6" Square - AC 352500EY is the conductive material you've known you wanted but never knew you could have. It’s a sheet of flex PCB material. This is the stuff used to make flexible circuits, but raw and unetched. You can treat it just like 1 oz copper clad, etch it with ferric chloride (or other PCB etching systems) or cut with scissors. It may even be possible to laser or CNC engrave.
One side of Flex PCB Material - Pyralux - 6" by 6" Square - AC 352500EY is 1 oz copper while the other side is polyamide for strength and flexibility. The material can be manipulated through and around small areas and won't crack as easily as copper tape. Pyralux is used in a ton of consumer-grade electronics and one of the reasons why things like your cell phones have advanced from bulky and cumbersome to miniature super computers.
Flex PCB Material - Pyralux - 6" by 6" Square - AC 352500EY comes with a 6"x6" (152mm x 152mm) square of Pyralux. It's ED-Y type copper at 35um (1 oz/ft2) and has a polymide of 25um (1 mil). The thick copper layer means it can carry a lot of current, and it’s trivial to solder to it.
Adafruit Web Site: http://www.adafruit.com/products/1894