Quantity   Component name
1 × NEMA-17 Stepper
1 × NEMA-17 Stepper with 5:1 planetary gears
2 × Stepper motor driver (A4988 or DRV8255)
3 × LM393 Dual Comparator IC
1 × Microcontroller (arduino or micropython)
1 × IR LEDs, matching wavelength photo-diodes
1 × resistors (1K, 33K, 10K variable), capacitors (47uF and 104s)