Grogyan's Stars
MarlinFirmware/Marlin
Marlin is an optimized firmware for RepRap 3D printers based on the Arduino platform. Many commercial 3D printers come with Marlin installed. Check with your vendor if you need source code for your specific machine.
prusa3d/Original-Prusa-i3
Original Prusa i3 MK2 3D printer printed parts
Smoothieware/Smoothieware
Modular, opensource, high performance G-code interpreter and CNC controller written in Object-Oriented C++
repetier/Repetier-Firmware
Firmware for Arduino based RepRap 3D printer.
machineagency/jubilee
jubilee source files; for the docs, see:
kliment/Sprinter
Firmware for RepRap printers and similar devices
e3donline/ToolChanger
STPs / STLs / DXFs / PDFs