Thanks for all the suggestions guys.
I'm a trained graphic artist for 25 years, so the printing part I should be able to get correct.
I measured the tube several times after I posted this, just to be sure the outer diameter was correct. It was spot on! The inner wall thickness was roughly the intended thickness, being shy of just 0.1mm of what I can read is optimum.
The size of the print should be correct, and so should all the holes on the print. It wasn't printet out of aspect either.
In the end I just gave up on finding out what the issue was. And redrew everything in Adobe Illustrator. And got a print that wrapped perfectly.
The tube has been cut, and the holes has been drilled. It is still in a very rough state, and will need to have burrs and cutting grease removed. I ran out of time yesterday.
I appreciate all you suggestions, and have also tried out all those. But I apparently can't figure what I did wrong with the original print.
I will soldier on, and post updates, and meltdowns as they occur!