This is a 3 piece toilet paper roll extender for larger rolls. The spring will fit inside the larger hollow tube section and the two pieces then press together with the toilet paper roll in between. The spring installs easier if you use a gentle rocking twisting motion. There is a slight taper to the end of the tube that should keep the spring from falling back out.

The spring is a modified version of this spring:No Support Needed Octagonal Compression Spring by nokiri - MakerWorld. I love that it prints without supports, and after finding this I didn't see a point in designing anything else. It just works.