3D Printer controlling software

• Repetier Host/Server http://repetier.com
• Pronterface/Printrun http://www.pronterface.com/
• OctoPrint http://octoprint.org/
• MatterControl http://www.mattercontrol.com/
• GCodePrintr https://play.google.com/store/apps/details?id=de.dietzm.gcodesimulatorprinter (Android)

3D Printer firmware

• Repeiter http://www.repetier.com/downloads/
• Marlin  https://github.com/bobc/Marlin/tree/Marlin_v
• Marlin4Due https://github.com/Wurstnase/Marlin4Due
  REPRAP Firmware
• Forum RADDS and REPRAP firmware http://forums.reprap.org/read.php?249,569411
• GitHub https://github.com/dcnewman/RepRapFirmware/blob/dev/doc/RADDS-v1.5.md

Slicers

• Slic3r http://slic3r.org/
• Cura https://ultimaker.com/en/products/software
• SIMPLIFY3D https://www.simplify3d.com/ (All in one)
• KISSlicer http://kisslicer.com/
• Skeinforge http://fabmetheus.crsndoo.com/wiki/index.php/Skeinforge

3D Design software

• FreeCad http://www.freecadweb.org/
• OpenSCAD http://www.openscad.org/
• SketchUp http://www.openscad.org/
• Tinkercad http://tinkercad.com/
• Autodesk 123D http://www.123dapp.com/design

Free 3D models

• Thingiverse http://www.thingiverse.com/groups/radds
• YOUMAGINE https://www.youmagine.com/
• yeggi http://www.yeggi.com/

Communities/WiKi

• RepRap.org http://reprap.org/wiki/Main_Page

Other software

• Arduino software http://arduino.cc/en/Main/Software (used to edit/update firmware)

Electronics

• dr-henschke.de http://www.dr-henschke.de/index.html
• Arduino DUE http://www.dr-henschke.de/index.html
• UDOO QUAD http://www.udoo.org/features/
• Raspberry Pi 2 Model B http://www.raspberrypi.org/products/raspberry-pi-2-model-b/

Other Controller boards

• RAMPS-FD http://reprap.org/wiki/RAMPS-FD
• SmoothieBoard http://smoothieware.org/smoothieboard

Tools

• RepRap Calculator http://www.prusaprinters.org/calculator/
• projectBuildr http://projectbuildr.de/