3D Models

Pinshape : https://pinshape.com/

Thingiverse : http://www.thingiverse.com/

GrabCAD: https://grabcad.com/

Hardware

Reprap Org : http://reprap.org/wiki/RepRap

Reprap Printer “Prusa Mendel” : http://reprap.org/wiki/Prusa

Reprap Printer “MendelMax” : http://reprap.org/wiki/MendelMax

Extruder : http://www.thingiverse.com/thing:8252 

Electronics

Sanguinololu Board : http://reprap.org/wiki/Sanguinololu 

RAMBo Board: http://reprap.org/wiki/Rambo

Arduino : https://www.arduino.cc/en/Main/Software

Software (3D Printer)

Cura (3D printer control): https://ultimaker.com/en/products/cura-software

Repetier (3D printer control): http://www.repetier.com/

Slic3r (slicing engine): http://slic3r.org/

Firmware: https://github.com/ErikZalm/Marlin/ (please use only the included firmware as it is tuned for our machines)

Software (3D Modeling)

FreeCAD : http://www.freecadweb.org/

SketchUp : http://www.sketchup.com/

OpenSCAD : http://www.openscad.org

MeshLab : http://meshlab.sourceforge.net (STL mesh editing, cleaning, healing, etc)

NetFabb Basic : http://www.netfabb.com/downloadcenter.php?basic=1 (STL mesh viewer and auto repair.  Check out their mobile app as well!)

Onshape :  https://www.onshape.com/