Don't take ANY chances on brakes as Grigg mentioned.
Yep, good flare tools are expensive, but You can buy a nice old style one for around 100 that will do anything you'd need but stainless, I have one made by Imperial that is OK. Have some of the cheap line Of OTC that I won't use, they sent a replacement and I never unwrapped it..
The one I really like is made by
http://www.sykes-pickavant.com/here's a catalog
http://sykes-pickavant.com.dnnmax.c...20-%20Brake%20Pipe%20Flaring%20Tools.pdf One chance I wouldn't take is single flares. Always use double flares on 45* flared brake lines, the reason is to lessen the chance of the flare splitting and leaking later on.
Grigg