This is easy to print, I recommend to use support on "static" part, then once printed and supports removed, to use a piece of sanding paper rolled in the length side to make a "tube". Then insert it in place of the filament and move it to remove small defects and ensure the filament will be able to move inside without to rub.
- Put the "mobile" part in place on "static" and the spring.
- Screw from the bottom to maintain them (not to tight).
- Screw near the spring and its opposite corner.
- Pinch the parts and screw under the "mobile" corner where the switch will be.
- Screw the rotating axe (also not to tight, but enough anyway).
- (if you have soldered one) Place the plug of the switch in its hole.
- Place the switch (and be sure to adjust it by bending a bit its "arm") and screw it.
- Screw the ball bearing (re-used from the original extruder feeder).
- (if you use one) Put the cover on it.
- Plug the stepper motor cable, and the runout sensor cable too.