Actually, it’s evacuation molding.
First, they pump a bunch of hot polyethylene that’s been compounded with excess paraffin in to the mold cavity, next they “rapidly” cool the tool to build up a hard shell, then they puncture the shell and pressurize it with air while leaving an opening for the molten core to be forced out.
I’d say it’s like a combination of injection and blow molding but absolutely not Injection Blow Molding, because that is a whole other thing.
It’s probably closest to slush casting or slip molding.
This little beauty however, was roto molded.
