This is a great project, with some flaws. I've shared ideas for possible improvements with the creator, but here are some advice for other folks trying to build this project. 1. Print the gear shaft, spool shaft and guide pins with as many walls as you can, they might break if things cease up. 2. Before putting the lid on the electronics box, test the direction of the motor by plugging it in, keeping the filament sensor pressed and pressing the start button. Compare it to the presentation video in the description and see whether you want to either swap the motor cabling, or reprogram the Arduino after changing the motor direction in the source. 3. Before the step that says "Add the left Frame L.", add the ball bearings for the worm gears into "Frame L". 4. Spend a lot of time trying to synchronise the filament guide on the 2 worm gears when installing that belt, and try it out unpowered by moving the motor belt by hand. Hope this helps.

Pretty impressed with the quality of the output from the provided 3MF, and a useful tool. Easy to put together if one follows the instructions ;)