Print 2 coins and 1 donut. Insert the tube into the donut with the coil around it. Heat the tubing with a lighter and press the filament pieces together and use the coins to apply pressure and prevent any expansion of the filament. No sanding necessary. Coil Spring https://www.amazon.com/Xianglaa-springs-Diameter-Stainless-Compression-Compressed/dp/B09DKZTT8R/ref=sr_1_51?crid=1WSUUVU7N5HY7&keywords=coil%2Bspring%2B3.2mm%2Bod&qid=1663861249&sprefix=coil%2Bspring%2B3.4mm%2Bod%2Caps%2C218&sr=8-51&th=1&tag=thingiverse09-20 Tubing https://www.amazon.com/Aicosineg-Teflon-16-4ft-1-8mm-Connector-Printer-Milky/dp/B092QR92XZ/ref=sr_1_5?crid=1LH9VR8P4MSNP&keywords=ptfe+tube+1.8mm+id&qid=1663859311&sprefix=ptfe+tube+1.8mm+%2Caps%2C204&sr=8-5&tag=thingiverse09-20