How to fix the lens in a plastic or metal pipe?

Question

Do it yourself

Hey!
For the past few days, the fix idea has not left me: to make a simple refractor telescope myself. But not from paper rolled into a tube, as advised on the Internet, but from a plastic or metal pipe. Initially black.
One question remains unclear. How to fix the objective and eyepiece lenses in this tube? With rubber pads? Wrap fum tape? Or something else?
Thank you!

Answer 1

Hot glue gun. Holds, gives elasticity and tear off if that is easy.
First, with any spacers to set the corners, then fill with a hot glue gun, pull out the spacers and fill in the places where they stood.