This is a 3D printable adjustable-length column that I designed to support a sagging shelf, but you can use it to support whatever you like. I made it for the second tier of my office shelving, which has started to bow over time due to lack of a more traditional mounting bracket. The lower tier is braced better with triangular wall brackets, but the upper tier needed something self-standing.

This column consists of five interlocking threaded components: simply twist the top section to extend the internal threaded shaft and fine-tune the height for a snug fit. No supports are required for printing, and it assembles fairly easily. Note that the top piece is reversed (left) threaded.

I printed on a Prusa Mk4S using Overture Rock PLA, which has a stone-like finish but is abrasive, so I used a hardened 0.4 mm high-flow nozzle with a 0.25 mm layer height. It works well as a visual and functional piece.

This is similar to my GPU support column model, but I completly redesigned things in fusion to be support free printable, much larger, hollowed to save filament and have smoother movement. 

Bonus is that the base and column is hollowed out so you can keep secrets in it!  It also looks kinda neat to place an led or two inside the column to make the print glow. Write yourself an affiramation on a piece of paper and place it inside the column…now it's an emotional support column - ba-dum ching.