[Dalec]

Figure out how much higher it is than you want it, like the thickness of the tube. Make a piece of stiff wire that is that length. Take a Sharpie and that piece of wire to transfer the contour to the tube above it. Hold the wire straight up, and cut away anything that it touches. There may be some spots like the upper end of the tube where you will need to be artistic.

 

[Dalec]

toilet paper roll?

it would be sweet if that worked out.