Bells which are rung are usually made by casting bell metal (a high-copper bronze alloy) of a size appropriate for the pitch the bell is intended to produce. Other materials occasionally used are brass or iron.
Fine tuning of metal bells is achieved on a lathe to remove a precise amount of material from the inside of the bell to produce a true tone with correct harmonics. Small cheap bells, of course, do not undergo these steps. Bells are used often in sets in handbell choirs, chimes or carillons and so must be well tuned in order to produce a correct scale of musical notes.
Bellfounders may create one large bell (such as the Liberty Bell). The largest bells weigh several tons and may be to be sounded by swinging only the clapper instead of the entire bell as swinging such large bells would cause structural problems for the towers they are housed in.
The process of making the large open end of a Brass instruments by a process of metal beating may be call bellmaking. In making the bells (open ends) of brass instruments, for example, trumpets, a person lays out a pattern and shapes sheet metal into a bell-shape using templates, machine tools, handtools, and blueprints. The maker cuts out the bell blank, using hand or power shears. He hammers the blank over a bell-shaped mandrel, and butts the seam, using a notching tool. The seam is brazed, using a torch and smoothed using a hammer or file. A draw bench or arbor press equipped with expandable lead plug is used to shape and smooth the bell and bell neck over a mandrel. A lathe is used to spin the bell head and to form a bead at tip of bell head. Previously shaped bell necks are annealed, using a hand torch to soften the metal for further bending. Scratches are removed from the bell using abrasive-coated cloth.