Industrial design students Andrew Duffy, Craig Tyler and Edward Harrison from the University of Rochester constructed a minature rotational molding machine out of scrap materials and a cordless drill. From their YouTube post:
DIY rotomold machine built whilst studying in our 3rd year on BA Product design. The video takes you through the journey as we built and tested the machine. The machine was built at no cost from scrap materials and recycled parts. This was not part of our degree in any way just a process that we wanted to explore and learn for ourselves.
Instead of requiring an oven and heat to melt (sinter) the plastic as in traditional rotomolding, the students used 2-part cold setting bio resins (UCA?) to produce hollow plastic parts. Check out the video:
They really seemed to have a great time with the different materials and processes. They used vacuum forming to make the mold halves for the rotomolding–most excellent! Check out these little piggy banks: