Place a ball mandrel inside the copper pipe. A ball mandrel is a series of steel balls held together with wire or cable. When placed inside copper tubing prior to bending, it will not allow the tubing to kink.
Insert the copper tube into a coiled-spring bender, matching up the section that will bend to the center of the bender.
Grip the coiled-spring bender at each end and use a clockwise twisting motion to form a bend in the copper tubing. Bend the copper tubing over your knee or a rounded object that has the same degree of arc that you plan to bend the tubing.
Ease the coiled-spring bender and copper tubing back to the exact angle you desire if your bend is too severe.
Measure and mark the ends and middle of the bend.
Lay a fireproof blanket over the work surface. Move all flammable objects from the area to avoid a fire. Secure the copper tubing to a sturdy work surface with a vise or C-clamp.
Heat the tubing with a hand-held propane torch until the copper glows red. Allow the tubing to cool back to room temperature.
Pack sand tightly into the copper tubing and cap the ends.
Bend the tube over a bending jig, circular object or your knee until you reach your desired bend. Intense heat changes the molecular composition of the copper, which allows for easy bending even if the copper tubing is soft to begin with.