Printed from PETG. 
ASA or PA might be better.

Body:
nozzle: 0,4 mm
layer hight: 0,2 mm
walls: 4
supports: no

Sealing (3 pcs):
nozzle: 0,4 mm
layer hight: 0,1 mm
walls: 4
supports: no

Assembly:
1) insert the PTFE tube into the seal
2) insert the tube and seal into the body until it stops
3) push the seal into the body to secure the PTFE tube in the body

All parts are very tight, be careful of damage, use appropriate force.