This is my take on a compact top mounted spool holder for the Monoprice mini delta. It uses the 4 holes for the handle as the mounting point. I personally used the original screws, but I included a printable friction fit pin to use in their place.

The holder was designed with filament usage in mind as well as not needing to print it on a separate larger printer. Although I wanted to minimize my filament use, I opted to modify this specific spool adapter(1) I found in order to use its potential to fit the small differences in spool designs. I also uploaded a copy with the center still solid so it could be scaled and edited as needed.

It uses almost no additional hardware, minus a single ball bearing in the center. The bearing screw is friction fit to the bearing so may need a little bit of force to insert. The bearing I used: 22mm OD / 8mm ID / 7mm H. I decided to use a bearing instead of going completely hardware free in order to prevent any noise from the 3d printed parts coming into contact as well as keep the rotation as smooth as possible.

It was also designed specifically for Polyterra cardboard spools as it was my only available spool to test with. There are 4 “feet” to support the spool while avoiding holes and keeping minimal contact to allow smooth operation. I also considered adding flat metal thumbtacks to these for even smoother operation, but ultimately decided it was unnecessary. The spool is supported ~9mm from the surface. The furthest point the feet contact the spool is ~53mm from the actual center of the spool.

I'm still dealing with mild elephants foot with my printer so, I had to scrape the bottom edges of the prints to get it to fit, but it really wasn't much and the pieces should fit perfectly.