(HSO) Filter. I created this 3-stage filter that removes both hard (H) and soft (S) debris, and also applies oil (O) to the filament.
I recommend buying some 1/8" push-in fittings for PTFE tube bowden if you'd like. It gives the setup a more professional feel, plus it keeps all the filters together as one.
Scale the STL filesto 1.3 on MatterControl