Have you ever 3D printed anything? Have you ever created a 3D model for anything? List one or more 3D file extensions.

3D printing (additive manufacturing) builds a physical object layer by layer from a digital 3D model—commonly via FDM (fused filament), SLA/resin, or SLS. The workflow is: create or obtain a 3D model in CAD, export it to a mesh/interchange format, slice it into machine instructions, and print.

Common 3D file extensions:

• STL — the classic triangular-mesh format for printing.
• OBJ — mesh format, supports color/texture.
• 3MF — modern XML-based format carrying mesh plus metadata, materials, colors.
• STEP / STP — precise CAD (solid B-rep) interchange format.
• AMF — additive-manufacturing XML format.
• G-code — the sliced output (machine motion/instructions) sent to the printer.