Actually, there is an extrusion machine that is available as a kit, for making objects using styrene. There is a series of videos on YouTube from a modeler who bought the kit and built the machine, then demonstrated casting pieces. For example, he made a model of Doctor Who's TARDIS, based on a CAD file.
The technology in this case comes from the medical field; it's used to make prosthetics and other objects in plastics or resins. Someone figured to make the machine smaller and package it as a kit. with the extruder and the hardware necessary to interface to a PC and read the design from a file. It also includes laser-cut plywood pieces to build the box. The results are OK, though, not spectacular. The piece had rows or ribs, from each pass the nozzle made as it extruded a bead of melted styrene. The finished piece would need some sanding. But the technology is improving, so it's conceivable that we could see something like that to make figures. It's still easier at this point to take a master and make a mold.
Prost!
Brad