In case you use tubes with OD4mm/ID2mm, you can use pins for security (against tubes slide out). Insert all 4 tubes as far as is possible (approx. 16mm deep), then use 2.5mm drill and go through one of the pinholes (or both). Remove drill and insert 2.5mm pin. The tubes should be secured well.
edit:
19.02.2025 - sensor position tuning
01.03.2025 - added 2mm to length of the 4 tubes
15.03.2025 - added longer version with 2 security pinholes
The author remixed this model.