I saw this rotational molder a while back on several blogs (Ponoko, Core77, designboom). Rotational molding is typically used to make large hollow plastic parts. They make anything from kayaks to gas tanks. The molds are very simple hollow cavities, that split into at least 2 pieces.
A specific amount of material is placed inside and the mold is heated. When the material is in a liquid state. The mold starts to rotate in 3 dimensions so the material evenly coats all the walls. The material in allowed to harden and the mold is split apart. You now have a seamless hollow plastic part. It has a parting line, or flashing, but the part is essentially seamless.
This machine is a beautiful example of flat-pack design. There is very little waste material. This version ditches the heating step and uses cold set resin. They recommend a two part resin called ‘Easy flow 120′. It is available at Mouldlife. It comes with a sample mold and you are on your own for the next one. It looks like the mold was vacuum formed.
It is called My First Rotational Moulder and is available for purchase at StudioMyFirst
(I guess they spell molding differently over there?)