The best way to coil your copper tubing depends on the type of copper tubing you are using and the diameter of your coil. You can coil soft copper tubing, such as refrigerator tubing, by hand without it kinking if you are careful. Hard copper tubing, more commonly called copper pipe, requires tools to bend without it kinking. With any type of copper tube, work slowly and carefully. Do not force the copper, or it will bend too sharply and create kinks.
Start with soft copper tubing or anneal hard copper tubing by heating it evenly with a blow torch on a heat-resistant surface until the point it just begins to glow red, then let it cool. The annealing process softens the copper, making it more workable.
Cover one end of the tube by wrapping it securely with masking tape, then pour fine sand into the tube, using a funnel. Cap the other end with masking tape when the tube is full. The sand keeps the tube from collapsing as it bends.
Wrap the tubing slowly around a hard form, such as a paint can or metal pipe, that is the same diameter as you want your coil. You should be able to bend the tubing by hand. Work slowly and gently.
Support the part of the tubing right before each new section of the bend by holding it firmly against the coil form with one hand. If necessary, tap the part of the tubing you are bending lightly with a rawhide mallet as you wrap it into position.
Remove the masking tape and drain the sand out of your copper coil.
Start with a very loose loop of your coil, and then tighten it to the desired diameter around a smaller form once you have a complete circle.