As 78buckshot said, you can buy copper-nickel alloy brake lines from you local auto parts store. Just make sure you match the existing line size so the replacement line fits the wheel cylinders and frame fittings. 3/16" and 1/4" are the most common size used on our trucks and it's easy to bend.
https://www.napaonline.com/en/p/BK_8131318Mike B
