you can "sort of " put the bulge in the line with a "double flare" flaring tool. YOu just do the first part of the part of the double flare. I say sort of because it is not exactly right like a correct bolge. I guess if one were to experiment a bit, you could customize the tool a bit a probably get it down to a science to the point where it looks like a factory bulged end. But for all intents and purposes, it serves the same function. What would be sweet would be to have one of those hydraulic flare tools lkke from inline tube. they advertise a "metric bubble flare tool" for $85 that supposedly makes the bubble flare in 5/16 and 3/8. (why do they call it metric though, i dont know?).And actually that aint a bad price if you were to do alot of the bubble ends.
