A 3D printer includes a chamber configured to receive extruded material to print a part and a tool chamber above the chamber, the tool chamber comprising a viewing window and a tool rack. The 3D printer includes a plurality of print heads, each of the plurality of print heads residing in a docked position on the tool rack and when not in use. Each of the plurality of print heads comprising a illuminated status indicator configured to emit a plurality of signals indicative of a status or error of the print head or a status of the 3D printer, wherein the illuminated status indicator faces the viewing window and a plurality of sensors located on the print head or in the 3D printer and configured to detect a status of the print head or other printer components or an error in the print head or other printer components.