Having reviewed many alternate models for allowing the use of external filament without needing to disconnect the AMS I found none that worked flawlessly whilst providing secure attachment to the rear of the machine.

This requires three PC4-M10 fittings with a 4mm bore. These allow the PTFE tubes to be pushed into the part providing a smooth path. The lower path, used for the AMS connection has a gentler curve to ensure perfect feeding every time, whilst the upper path can tolerate a slightly sharper bend to clear the mounting as manual feeding of the filament is more forgiving.

It is attached to the back of the printer using two M3x8 button head bolts.

The part should be printed in the orientation shown in the project file. The three openings need to be tapped after printing for the M10 fittings. I got a great result using ABS, but any filament should be fine so long as it can be tapped.