To mass-produce something is to make a very large number of the same object in a factory, with machines, so each one looks like the next and the price can stay low. Car makers mass-produce cars; phone companies mass-produce phones. The idea became famous in the early twentieth century, when factories learned to run a moving line and stamp out parts. Though actually this word is the action the factory does. The finished objects are mass-produced. People in business and news use the verb all the time. It is a little stiff for chat, but not rare. Handmade things are the opposite idea: each one is slightly different and usually costs more.