"Same guide with insert slot for 1,75mm filament
Print with 100% infill."
Commenters noted that filament tended to pop out of the guide in the original version, so I simply flipped it. I haven't fully vetted it yet, but seems to work out so far.
Update: When printing from a full roll, filament pops out of the guide when the extruder is going to X0 for homing.
The author remixed this model.