This model adapts the “reusable” Sunlu spools to Bambu refill filament compatible ones. I was dissatisfied with the pre-existing options, they either relied on a friction fit between one of the ends of the spool, were way too loose and fell apart easily or used some complicated threaded solution that required a lot of filament.

This design makes use of both ends of the spool lock, making it very sturdy while keeping the material requirements down. The RFID tags are also functional with this solution. 

Important note: Sunlu spools can vary in size, but I don't know if this only applies to the bulk spools (3kg and up) or even the smaller 1kg ones. If you want to stay safe, please measure the width of the filament storage part of the original spool, this model should support 50mm ones.

The following models are included:

• Regular spool adapter: Provides a sturdy connection with both the filament and the AMS unit. The model only requires 66g of filament and prints in approximately 2.5 hours. Choose this option if you're unsure.
• Spool adapter: Cheapskate edition: This version cuts out all the technically unnecessary parts of the connector, cutting filament usage by half to 30g. Print time is also reduced to about 50 minutes. Choose this if you're in a hurry and need a new spool of filament, are very  stingy with materials or if you have a print farm and need a dozen of these.
• Label holder: This optional accessory lets you make use of the included material stickers and it even keeps the meter accurate, or at least as accurate as a linear scale can be on a cylinder.

Assembly instructions:

Assembly is the same between the regular and short adapters.

1. Take the Sunlu spool apart. Grab the two sides, one with each hand then twist the top of the right side towards yourself and the top of the left side in the opposite direction. They should pop apart quite easily.
    

   

2. Place the shorter end flat on a surface and note where the hole placed into the central cylinder is located.
    

   

3. On the bottom side of the adapter (the one that was touching the build plate) find a small circular indent.

4. Place the adapter on top of the end of the spool with the circular indent above the hole and slowly rotate it counter clockwise until it falls into place. Twist the adapter clockwise until you feel a small click.

   

5. Remove the filament from the vacuum package and locate the small cutout in the cardboard section. At the same time find the small knob sticking out from the side of the adapter.

   

6. Place the filament on the adapter while lining up the cutout with the small knob. You can spy at the connection from the side and through the spool if you can't see it properly. The filament should end up perfectly flush with the side of the spool.

   

7. Take the other end of the spool and place it inside the adapter hole. Rotate it around until it falls into place and twist it counter clockwise. The spools are keyed to a specific orientation, so if you can't quite get it to click, try other rotations.
    

   

8. Remove the plastic strips holding the filament together. Make sure to immediately thread the end through one of the side holes or insert it into the AMS.

Optional steps, installing the label holder:

1. The optimal side to install the label holder on depends on how you place it on the AMS. It should preferably be on the end that looks away from it.

   

2. The holder has two cylinder attachments, these go in a pair of holes from the ones marked on the following image:

   

3. Once the holder clicked into place, attach the sticker. Make sure the arrow points towards the center of the spool.