edit 2023-01-10: Uploaded .F3D and step files of original part.

edit 2018-05-16: Increased the internal and external diameter 1mm. Decreased the width by 0.5mm. Now dimensions are internal 91mm, external 103mm, width 54.5mm.

Will work on putting some arms on it to see if that makes a difference too.

Link to MasterSpool thing.
Link to another eSun spool adapter done by user JAYTEEAU

edit: Fixed the orientation. Also will probably fit some other spools that have a 90mm diameter core. Height is 55mm.

eSun Spool Adapter to help make refill rolls fit better.

Shouldn't need supports, not yet printed so dunno how it will go.

Print instructions

Rafts: No

Supports: No

Resolution: 0.15

Infill: 20%

Notes:

Yep definitely fits better now. It's a tight fit, if you are going to use it make sure a) you put it the right way up and b) slide the bump on the inside into the notch on the spool. Not that it will spin around anyway (friction fit) but hey thats why its there.

After mounting the filament on and putting it together, secure the end of the filament and give it a shake. The filament will settle into the wider gap without too much issue.