As we known, the big advantage of Blow Moulding is being able to make hollow items.
What's more a seamless hollow item, not something made by joining two halves together. Blow Moulding is a much cleaner simpler way to be leak free. Great for putting liquids in.
So an ideal process for making containers, bottles, fuel tanks, IBCs, kayaks, flotation devices.
It's even possible to mould in handles too.
The only other common method to make one piece hollow items that we can think of is Rotational Moulding, which is a less precise process and it’s slower cycle time cannot compete with that of Blow Moulding.
At which point let's note that there are two distinct methods for doing Blow Moulding.
Extrusion Blow Moulding
Injection-Stretch/Stretch Blow Moulding
The former is the standard method of Blow Moulding while the latter is a method specific to the making of PET soda and water bottles.