Matching Pairs Materials for technical useOnline version What is involved in making a mobile phone? Match the following elements. by Jesús Espinosa 1 The outer casing of mobile phones is typically made from... 2 How much does it cost? 3 How big is it? 4 What is it for? 5 What materials is it made of? 6 How does it work? Plastic, aluminium and other metals For people to talk to each other from wherever they are. The average price for a free smartphone is currently anywhere between 400€ and 800€. Nowadays the average is more than 5 inches long (12.7 cm). plastic (polycarbonate), aluminium and magnesium. They work like two-way radios: the phone converts the sounds of your voice into radio signals and transmits them to another phone, which converts them back into sound.