Do you make a lot of custom brake lines? You should get this brake flaring tool. It works so well its difficult to image using the older style. It’s made by BrakeQuip and it’s good.
You simply clamp the tube in the device, select the right size flare and pull the lever. Boom. done. You can check out the rest of their products on their site. brIf you’re wondering how it works, check out this video: