Measure 12 inches from the top of the tank and make a mark on the side of the tank. This is going to be your cutting line.
Cut off the bottom off the aluminum tank using a miter saw with a metal cutting blade. Cut through the material very slowly while providing a small amount of pressure on the blade. If you push the saw too hard, the blade and the tank will heat up, causing premature wear on the saw.
Thread the 3/4 inch to 1/4 inch reducing coupling into the top of the tank. This will become the mounting location for the hanger hook.
Thread a 1/4 inch hook into the top of the tank. Hang the tank from a rope outdoors, or in any location where you wish to display your new bell.
Create a bell mallet by wrapping the end of a 12 inch piece of pipe with electrical tape five to six times. Hit the mallet to the side of the bell to make it ring.