Update 12Jun22: Version 2 added. Frame mounting tab made narrower to help clear parts of an LED light strip (if used). Mounting hole recess also removed so bracket can be turned around if desired.
Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5397700.
Wanting to use my eSun eBox Lite filament dryer box with my Ender 3 S1, and looking forward to setting up an enclosure (at some point) in the future, I designed this bracket that allows for fixed placement of the runout sensor with the filament feed arrangement being highly flexible. There are a few other designs and I was partly inspired by those.
https://www.thingiverse.com/thing:5346708 https://www.thingiverse.com/thing:5363897
This is a fairly simple design with minimal parts needed. I had 2 M6 brass tube fittings (sorry I don't know the technical name) lying around so the fitting holes are designed with those in mind.
The bracket is mounted to the frame by removing the end cap. There is a threaded hole for an M5 screw in the center of the aluminum extrusion, and this is perfect for mounting the bracket.
Finally, I added 2 short pieces of PTFE tubing on each end. The only recommendation here is to experiment with the length you prefer for your setup.
Thanks and let me know any comments!