Spool holder for Anycubic i3 Mega

This is a remix of https://www.thingiverse.com/thing:2734209
by ltlowe Dec 27, 2017.
I found that the filament guide was too close to the filament detector when the head was near the heated bed.
The filament detector was constantly detached from its magnetic base.
So I pulled back the filament guide and lowered it.