Andy. very easy, get a roll of copper pipe,£25 squids for 15mtrs or thereabouts and as said buy a flaring tool /kit, and just practice, oh you will also need a tiny pipe cutter also , you can buy these from b AND Q , it ensures a perfect round cut..
Having quick look around, i found this on flea bay, Same as mine and very easy to get a perfect flare
Ebay title.....Sykes Pickavant 270 series brake pipe flaring kit 02700100
a looks a good deal with a small pipe cutter etc etc,there you can always sell it afterwards
1 x Sykes Pickavant 270 series brake pipe flaring kit 02700100
*1 x Mini Tube Cutter 3 - 22mm
*2 sets of dies included
*1 x 25 foot roll of new sealed brake pipe
*10 x Metric Male Brake Pipe Unions
*10 x Metric Female Brake Pipe Unions