They were originally used by bands (rock and roll) that were on tour and needed to transport their equipment.
They would use these cases to move their instruments, lighting equipment and sound equipment.
Today these cases are used by a lot more people for things like Military uses, medical reasons, Film & TV, Touring and many other instances.
These cases are usually made from plywood sheets (phenolic or with aluminium layers, sometimes plastic layers are used).
The sheets are held in place by the use of rivets and aluminium extrusion profiles.
Galvanised steel is used to make the Hardware Fittings.
Catches and Handles are often recessed types.
The cases are manufactured slightly different, they are fitted with castors.
To give extra protection to the contents being transported shock absorbing foam can be lined along the inside of the case.
These cases are fully customisable and are made to meet your specific requirements, whatever size you require them, they can be made to.
It is quite common for these to be produced singularly where as a lot of items will only be made in mass production.
The holes that are cut into the flight cases are done by CNC machinery and are designed to be used as catches and handles.
The assembly of these cases is usually all manual with machines only being used to cut the sheets and profiles.