In the parts list for Lowerider2Cnc the link to Amazon has Stainless Steel 316L Welded Round Tubing, 1" OD, 0.902" ID, 0.049" Wall but on the same page on the right side it has These parts only for 25.4mm OD tubing for now, I recommend .065″ wall thickness stainless steel. What is the right tubing to use?

The amazon link seems to keep changing since it is a variable link. The important part is the OD, and no less than 0.65" wall. That should be safe. Default to the website for all info.

1" = 25.4mm