Brake line is normally sold in rolls of 25' over here, and I find that's plenty to do the job on a tandem circuit with no servo (boosters) or pressure warning switch.
If you have a tandem circuit and are installing 2 boosters as per Lotus OEM then you'll need considerably more because you'll have three lines along the central spine plus all the clutter around the boosters and pressure difference warning switch. As brake line is so cheap, if you have this system then I'd be tempted to buy two rolls (50') which will allow for several mistakes !
As the others have said, you can buy both pure copper and a copper alloy called "Cunifer" (or "Kunifer" ). Pure copper is very easy to work and can be annealed to soften it if you make mistakes on the bends. However it is prone to work hardening which can lead to fatigue failures, which is why the Kunifer is usually prefered. I've used both but pure copper must be securely fastened to the frame at closer intervals with no unsupported lengths that could vibrate in use. It's that vibration which leads to work hardening/fatigue.
Brian
