A filament load guide that sits just in front of the spool holders on the Prusa MMU2S enclosure. It uses PC4-M10 pass-through adaptors that you can run straight to the buffer. This makes loading the filament to the buffer easier and tidier and I find it reduces friction when using 2.5mm ID PTFE as it keeps all the bends smooth. Complete with screw covers.

The hole at the back isn't threaded as I've found out that there are a number of M10 pass through connectors out there with different thread pitches, plus the thread itself is tapered so it's a sod to model. The hole is sized to allow the adaptor to easily self-centre and cut it's own thread without damaging the item.