Step-by-step procedure

The aluminum foil tube is made from at least two layers of heavy duty foil formed on a cardboard tube and taped to make a cylinder.

Note a plastic tube with a stiff wire wrapped around it to keep the bend in place may substitute for a copper tube. Note that in the assembly below, the tube is inserted into the stopper and then affixed with tape to the aluminum foil tube. Make sure that the tubes are taped securely. Once the system is heated, adjusting these connections is not advised.

The aluminum tube is supported at the upper end by the vessel, stopper and tubing. The lower end is held up by a cup placed at the bottom as shown below. Also shown is the wet paper towel draped over the aluminum foil tube and allowed to dangle in a pan of cool water.