Some of you may not be aware that I own a business, Riffgan Restorations, part of which is restoring old vehicle components. The business started because a small segment of people knew what I was doing with motorhomes (as well as other vehicles) and wanted me to do likewise with components of their projects.
At the start of a job, I divide all the parts into three categories:
1. Parts that can be simply replaced, with OEM or aftermarket products.
2. Parts that can be restored to like-new (or better-than-new) condition. Specifically, parts that cannot be replaced and must be restored to complete the projects.
3. Parts that must be custom manufactured, because the replacement parts are unavailable and the existing part cannot be restored.
The fact that I have a proven track record of accomplishing things that are generally considered impossible is why some people seek my services.
Brakes are one area that I avoid like the plague, due to the immense liability issues.
I have the tubing, fittings, adapters, and tools in my shop for fabricating brake lines. However, I will not fabricate lines for anyone other than myself. I will sell the components and rent the tools (with a hefty deposit), provided the customer signs a statement acknowledging risk and accepting sole responsibility for his or her efforts.
When I make a brake hard line (for myself), I always waste several inches of tubing practicing the flares, to make sure I can still make a strong, pressure-tight connection.
Compression fittings may work on water, propane, and compressed air lines. Compression connections on brake systems are extremely risky. In my opinion, such connections will fail, sooner or later. The connection is simply not strong enough for brake line pressure.
I replaced the air line between the compressor and tank on my air compressor because the original compression fittings failed. (Noisily and catastrophically.) For the replacement air line, I used flare fittings and added a shock-absorbing loop because a right-angle turn is part of the reason the original line failed.
The air line was simple, with a single piece of tubing and two connections. Brake systems are significantly more complex, with multiple tubing, connections, components, and branches.
The failure of the compressor air line was a minor inconvenience. On the other hand, a brake line is most likely to fail precisely when you need it most ... and could lead to serious injury or death.
When I use copper tubing on a propane system, I use single flare connections because propane systems are low pressure. For brake systems, I rely almost exclusively on double flare connections.
The risk is yours. If you make your own brake lines, and chose to cut corners, please stay out of Alaska ... I don't want to run across you on the road.
