I know raw styrene comes in a pellet form that is then heated and formed to the desired shape. It may be too hard to convert to a filament, which is what 3D printers use.
Thanks for the links. Definitely worth a read. I had no idea that there were so many options for materials.
To the OP, apparently ‘styrene’ in various forms is already in extensive use in 3D printing. I lack the technical knowledge to fully understand the differences between the various materials, as I suspect most of us do, but obviously several of the available 3D printing materials are compatible with the sanding/painting/gluing… involved in model building.