available on ebay in various sizes in polypropylene from this supplier https://www.ebay.com/itm/Polypropylene-Pipe-Tubes-Clamps-Green-Insulators-OD-1-2-Lot-of-10-pairs/263348582221?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 Why polyamide? Grant KZ1W