Hey Nick, If you are planning on doing custom lines in a bunch of sizes, like all the fuel and brake lines, AND you don't mind spending a little cash on good tools, then there is a really good kit from Eastwood. I wish my store had a supplier that sold this.
I don't know if we are allowed to link outside retail sites but if you look up "Eastwood Professional Brake Line and Tubing Flaring Tool" that should get you there. It is a turret style, so it mounts in a vise to make it nice and stable. It will do multiple sizes, and I think it does 45° inverted double flare and the bubble flare you see in metric applications.
I've used both the old clamping bar style and this and there is no comparison. Super quick and easy to get a good, straight, flare. I am going to pick one up the next time I do a big brake job.
I think there are a lot of copies out there, and I know of some expensive professional kits that use the same design but I can't attest to any of those.
