Here's a budget flaring tool that could get you out of trouble.

Not recommended for brake circuits. 

Includes clamping bar, flaring yoke and five dies for 3/16", 1/4", 5/16", 3/8", and 1/2" O.D. copper, aluminium or brass tube.

Best used on the bench in a vice but can be used freehand with some care and dexterity.

5/16" (8mm) copper pipe shown in example

NOTE: LUBRICATE ALL THREADS AND TUBE END LIBERALLY.

PIPE DOUBLE FLARING KIT #PIPFLARE2