Simple sealed passthrough with M6/ M10 Push fittings.
I highly recommend the M10 verison over the M6 one.
O-Ring: 14x2,5 mm or print the sealing with a very soft filament.
This Passthrough is specaial because it will allow you to insert the filament through the Passtrough without anny clogging. A problem I had with any other passthroughs I tested yet.
PS: Here I have a fitting Cap for your PTFE Tubes:
https://www.prusaprinters.org/prints/98167-ptfe-tube-cap-to-keep-the-filament-dry-tube-holder
Update 2022: increased the tolerance for the Filament passthrough (1,8 mm -> 1,9 mm)
Added a Version for M6 push fittings.
Update 2024: Added a Version for 2,5 mm PTFE tubes (like Bambulab uses)