On Nov 2, 1:56 pm, Tim Shoppa wrote:
In my garage, from some past project, I found some thin-wall white
(probably PVC) plastic tube. About the same diameter and a little less
thickness as 1/2" copper pipe, but plastic.

It was way way way thinner wall than schedule 40 PVC pipe. So thin
that it's somewhat transluscent.

What is this stuff called and what is it supposed to be used for?

If it's 1 1/4' or 1 1/2" diameter it is Delrin drain pipe for lavatory
or kitchen sink. Used in place of chrome plated brass usually. HTH

Joe