See an aerosol production line

This is an interesting enough video for anyone who wonders how aerosol hairsprays, sunscreens, or deodorants are made.

This is an example of a slow speed filling machine. It's slow enough that a worker can add the dip tube and valve prior to crimping. In this particular system, the valve is crimped while the can gets filled with the correct amount of propellant.

There aren't a lot of places that fill aerosols for cosmetics because it can be a bit dangerous dealing with potentially explosive products and chemicals.