It is a big surprise for most who did not assemble "Prusa Mini +" kit that there are actually three bowden tubes involved in the extruder block. One for filament loading hole, another one from extruder output to hotend, but there is third one approx 15mm length inserted inside extruder to guide filament from wheels to output brass mount. So I really do not understand what was the problem with making simple straight-thru bowden tube fitting for extruder output instead of separating it with brass mount and have two pieces instead.
So I decide to make simple adapter for most common bowden straight-thru fitting.
I still do not understand how people determine "PC4-M10*0.9 Straight-Thru" and "PC4-01 NPT (1/8in) Straight-Thru" Bowden fittings, but M10x0.9 thread works good for both so I took one from separate Capricorn upgrade kit for Creality machines.
Be careful during screwing it in because over-tightening will cause snap inside your printer extruder part. I would even recommend to print some extra "R1" extruder part for exchange like I did.
You can read more on my web-site:
http://tennojim.xyz/article/prusa_mini_plus_upgrades
The author marked this model as their own original creation.