Use CA glue and wood glue for the best bond.
I Didn't use wood glue due to time.
Slide all rings on tube. Stand tube on end on flat surface.
Slide 1 ring down to the end of the tube, flat on the surface. Carefully apply wood glue around the very outside edge of the ring. Leave 4 or 6 tiny spaces in the glue spaced evenly around the ring for a few dots of CA. Be careful not to use too much of either glue. You do not want to get it on the tube.
Note: some kits have more rings than others.
Press one of the other rings down on to the ring you just put glue on, be very careful not to squish glue on to the tube.
Repeat the same with the remaining rings.
You do not have to use CA if you are worried about gluing the rings to the tube. Just use wood glue and wait for each to dry before removing from the tube.
Strong rubber bands can help you hold the guide while cutting the tube.
Message me if you have any questions or concerns.