Hi Charles there are several types of flaring tools available. The simplest is the “hammer type” that you insert this into a filed and reamed piece of copper tubing and hit with a ball peen hammer to make a simple single flaire @ a 45 degree angle.
Then of course you can go for a double wall flaire (some times called a double lap) for higher pressures like the high side of an air condition system, but for this type you would need to buy or borrow a block and spinner AND you also have to decide which SAE (society of Automobile Engineers) flaire angle you want. 45 is the norm in plumbing But some folks use the 37 degree. Unless you expect really high pressure fluctuations I would go for the 45 Degree SAE-Nominal water tube which can be had in sizes ranging 3/8-1″ OR if you need up to 2″ flaire like a copper water main connection then you have to use the hammer type flaring tool with the 45 degree. Just remember to ream the tubing and file the ends.
Good luck
SylvanLMP