As I have said before I really battle with tube rivits. So when my husband brought some copper tubing home from the aircon guy. I thought it would be perfect to practice these skills.
I drew the tubing down - from about 6mm outer diameter to 2.5mm.
It does help that the tube is seamless and the walls of the tubing is quite thick.
I stuck it in my vinegar atmosphere for 2 days - I really like that green - and sealed it with a clear spray on varnish.