If you want to expand your home manufacturing arsenal, here is a very useful machine that will enable you to make hollow objects from various types of resin.
This machine is easy and cheap to make from 3d printed parts and 15mm MDF sheets cut on a CNC machine. It was published on Instructables by Jorge Dorantes.
It is hand cranked, but it could probably be easy modified to run with a simple electrical motor.
All the files and instructions can be found at:
If you are not sure how this machine works, here is a demonstration video of a different rotational casting machine by TGS Props where they use two piece silicone mold and Smoothcast 65D resin to make, well ... raptor / alien eggs!