Figure 1.

Diagrams of extruders for (a) fused filament fabrication (FFF) 3-D printer and (b) toy 3-D pen. Both devices use a motor and gears to feed solid filament into a heated nozzle and extrude the melted plastic onto a surface to build a physical object. The extruder on a FFF 3-D printer is computer controlled and moves in the x, y, and z directions to build a shape. The extruder on a 3-D pen toy is hand-held and moved manually by a user to build a shape. Drawings are not to scale. (c) Photograph of experimental set-up for a toy 3-D pen. (d) Photograph of experimental set-up for a toy 3-D printer and printed rose flower stem object. (e) Schematic of experimental set-up.