Telescopic Cylinder, seven stages, with 45° stoppers, diameter = 80mm; 60mm, height = 50mm; 20mm; 100mm.

Telescopic structures are simple yet mathematically appealing. I was playing with telescopic structures and came to realize that the stoppers inside could be made from 45° angles for smooth printing. The design process (on Fusion 360, for example), is fairly easy. K-12 students could learn how to use variables (parameters) for flexible design, constraints for intended geometric shapes, and rotation (revolving) for 3D construction. This is an entry-point 3D design project, featuring structures that are traditionally impossible to make in one piece. The result, however, is aesthetically motivating.

Have fun!

Reference:

https://en.wikipedia.org/wiki/Telescopic_cylinder