Melted plastic is shot into steel molds to make the housing halves, handle and nozzle. Plastic replaced metal shells in the 1960s and cut the weight.

Bare coiled nichrome wire is wound around insulating boards of mica. Nichrome resists corrosion when red-hot because it grows a thin skin of chromium oxide.

A small motor, usually a universal motor, gets its fan pressed onto the shaft tip. The pair is checked for balance and vibration before it goes in.

A circuit board, switches, a thermostat and a thermal fuse are positioned around the heater. They cut the power if airflow stops and the coil overheats.

The heater sits behind the outlet with the motor and fan behind it. The power cord is clamped in, and the halves are screwed together to a set torque.

Each unit is checked for dielectric strength, leakage current and temperature rise. Cord pull and button life tests run on samples.

Batches run nonstop in aging rooms to shake out weak motors before shipping. One factory has 12 rooms, each holding about 50 to 100 units.

Diffusers, concentrator nozzles and manuals go into the carton with the finished unit.