Update:
The gear module has been changed (the teeth have been enlarged) for more reliable engagement, which allowed for an increased rail gap. Now, the rails should insert smoothly when printed on most printers.
The main nut has been modified: its diameter has been reduced to prevent collision with the body, and the clearance has been adjusted for easier screwing. The knurling pattern on the nut has also been changed.
If you find that the fingers fit too tightly, try printing with no more than two perimeters-this will leave cavities inside the phalanges and hand, allowing the material to flex during assembly. You can also print with a -0.1 or -0.2 offset to compensate for over-extrusion, or calibrate your extrusion flow. I cannot set a smaller gap in the model, because for those whose flow is calibrated in the opposite direction, the fingers may disengage.
Springs: Aliexpress
You will need at least 2 kg of plastic to print at 100% scale. The files are optimized for printing on printers with dimensions of 200x200x200 mm or larger.
The sizes of the finger springs are as follows:
A: 66 mm.
B: 108mm
C: 110mm
D: 107mm
You can print using PLA plastic, 2 walls and 10% infill are recommended. It is better to print the springs using PETG.