Prusa i3 MK3S+ Filament Switch Ball Bearing Holder (Modified)
If you aren't having issues with false filament run out events or haven't tried replacing this block with a reprint of the stock version first, I wouldn't suggest that you jump straight to this fix.
Modified to reduce the number of false positive filament run out events. I had been suffering through many false run out events. Replacing this block in stock form solved the issue for about a month of printing non-abrasive materials before the issue returned.
Since then I haven't had a single false positive and all real run outs have been captured properly.
I suggest printing out of PC.
The author remixed this model.
Moved filament hole ~0.15mm closer to the optical sensor side of the print head in order to reduce the number of false filament run out events.
I've only been running this mod for about a month, but I haven't had any false positives with this modification and the printer has been stopping correctly on spool run outs.