Talk to the designer if you want the parametric version... ;-) This is for ABS plastic, and food grade 5mm silicone rubber tube. The design is based on this clever guy's work:http://www.thingiverse.com/thing:53451 Read the info on how to print it on a RepRap. You need to print the ring first, and adjust the mandrel gear scale to apply the correct pressure to the tubing. This step is crucial as ABS plastic will shrink at differing rates as it cools. This design will correctly fit together, but may only be a small puzzle. Note, both halves must be pushed and rotated in at the same time. The 3mm holes for the photo sensor and LEDs may require drilling to clean.