The "Crammer" is a prototype that is a work in progress, and is not yet fully developed for commercial use with re:3D's 3D printers like the GigabotX or other printers.
Helen: I used a NEMA 17, part number MT-1702HS170PG518-R from MoTech. I did have some issues on the firmware side with getting the auger motor to turn in concert with our 3D printer's extruder, and I ended up hacking Marlin's ditto printing feature, which means I didn't have fine control of the Crammer motor steps. Would be interesting to see how you implement that aspect.