Because I don't trust the weak locking mechanism of Recycling Fabrik's published spool (https://www.recyclingfabrik.com/pages/multispool), I have created this small piece of plastic to prevent it from accidentally opening. It was inspired by the locking chip that Bambu Lab recommends for their self-printed spool.

However, I can't recommend the MultiSpool for AMS. Even though the spool is now securely locked, their own refill coils fit loosely on the spool, and it lacks holes to fix the filament in place. As a result, the filament slips, causing the AMS to work excessively to rewind it. I recommend using a Bambu Lab spool instead.
 

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