The object is from the bottom up by layering extruded plastic. The nozzle that dispenses this plastic moves back and forth, just like a printer that has the ink nozzle slide back and forth on the carriage.

"Scuplting" implies something being carved away from a block of larger source material. 3D printing builds an object by adding layers of material in the exact pattern of the object.

In trying to figure out what I was trying to say, I found the following on wikipedia: "Durable sculptural processes ... used carving (the removal of material) and modelling (the addition of material, as clay) ... A wide variety of materials may be worked by removal such as carving, assembled by welding or modelling, or molded, or cast."

It seems that building up the material could fall under sculpture, which is called "modelling."

Maybe we should call them 3D modellers instead of 3D printers. Except that "3D modellers" is kind of ambiguous. It sounds like a person who makes 3D models.