Hi, I believe mostly use Acetal Homopolymer / Delrin Rods. Check Delrin Sheet, Delrin Rod, Acetal Sheets, Rods, Bars, Plates - https://iplasticsupply.com/home/plastic-materials-list/acetal-delrin-celcon-basf-pom-pomalux-sheet-rod/ and also someone said that he used ABS material which is much...