I can get 1.8x2.2 mm PTFE tube easily. Thus, I made the same design and share it.

To combine the 2 piece, you would need:

1. flat(countersunk) screw M4x12mm   x4
2. bolt M4   x4

Printing with support by normal PLA setting. If the screw or bolt is hard to place, try to adjust flow or you can just warm the holes with torch and squeeze them in.

Printing with half-cut PTFE tunnel upward is highly recommended.

Please refer to Pete Prodoehl's great demonstration video before use. It takes time to practice, but it's really fun!