Aluminium was developed first in 1825 but it was in late 1886 economical produced. Aluminium is almost always alloyed in uncountable variations in properties. The injection molding process gave the aluminium the big boost as material used for as well ground plated as cases of calculators. Aluminium plates were processes by thermoforming or stamping to make parts of cases as well. Those were screwed to each other or to the special formed ground plates.