planetary for nema 17 (accoppied with bond tech extruder)

planetary

sun gear m1 t10

original project
https://www.youmagine.com/designs/planetary-gearbox-extruder

for sun gear i think you can use also

http://www.hobbyking.com/hobbyking/store/__45522__10T_5mm_M1_Hardened_Steel_Pinion_Gear_1pc_.html