We always print this with 3 perimeters to make it stronger.
To get better results with the M3 holes in extruder_base we closed them with 2 layers. Just open them again with a drill.
Beside the pla for printing the parts you will need the following parts:
1x MK7 gear for 1.75mm filament
2x M3 self locking nuts
2x M3 40mm screws
3x M3 25mm screws
1x PTFE fitting PC4-M5 (M5 screw, for 4mm ptfe tube)
1x Nema 17 Stepper Motor
Finding the right tension
This Extruder is supporting a wide spectrum of different filaments.
Usually you only need to tighten one screw, which makes it more easy to find the right tension. For Filaments, that need to get squeezed quite hard, like old PLA or Ninjaflex you should tighten up both screws.
For printing Ninjaflex, you may print the Extruder Base with a nozzle as fine as possible and with a 0,1 mm layer height.