This is a remix of "Spool holder for Anycubic I3 Mega" by kurioso.
I really like the original, but the parts were a little loose and I had problems with the spool not staying on and filament getting tangled.

I've made the following changes to the arm

• moved the spool closer to the Z-axis mount
• tightened the z-axis post clip so there is less play
• thickened the spool holder arm slightly so the cylinder fits tighter
• modified the brace to be at w 45 degree angle rather than horizontal at the top so it prints without supports and still provides strength near the top of the arm where the twisting will happen.
• and maybe the most important change, I've added a filament guide.

The original cylinder fits this arm so I did not include the cylinder model.
The arm from https://www.thingiverse.com/thing:2681737 also works well. I have one of each.

Since I had issues with the arm twisting and spools coming off of the original model, I wanted a bigger lip on the spool cylinder. I didn't want to print another cylinder so I modeled a small lip piece to glue on the original. I've included this part as well.

I noticed someone asked for kurioso's fusion 360 model. Since I converted the original arm to a solid to make my changes, I've included the 123d design files as well.