The filament on my printer was making some weird scratchy noises when it was printing and I pinpointed the problem down to when it was entering the runout sensor. I found a snap on guide for the runout sensor so I could attach a bowden fitting but wasn't able to find a suitable mount for the other end. This was my solution. It was specifically designed for my CR6, but I guess it would probably fit any printer with a 20mm extrusion on the top beam.

Extra bits you will need - 2 x M4 * 10mm screws, and 2 x M4 tee nuts. 2 x PC4 M6 Bowden tube coupler and Bowden tube

You can probably use any top mount spool holder the one I use I found on thingiverse here.

The snap on guide for the runout sensor is here.