This is a post support with flange mounts on the ends.  It uses a bike seat post quick toggle clamp to lock in a position.  I built these make and adjustable infeed support for my miter saw. For my case I just let the support post pass thru the split clamp.  (See picture)

I added a longer version of the split clamp so you can use to make this taller or keep the post from passing through the flange.  This should be pretty easy to remix  to get the length to suit your needs, but post a comment if you need help making a specific height set.

This works with a bike seat post clamp like these from amazon.  They are pretty inexpensive  https://www.amazon.com/gp/product/B07WMSQ4LR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8  Note there is a small lip on one side of these clamps, so they only fit one way.  The lip does keep the clamp in place when it is not engaged.

The flanges are drilled and counter sunk for drywall screws.  The *.3mf files are 15% gyroid with the mounting holes reinforce with 60% gyroid.  I used PETG because I wanted the flexibility under the clamp.

May 2025 - added a beefier version.  Solid post, thicker walls, and thicker base, and extra material at the  base of the split clamp.  I used these for an adjustable outfeed support on a miter saw, and the lighter version didn't last supporting 2x12 lumber.  The *.3mf of the new version uses 40% gyroid from 0 to 24mm, and 15% gyroid over 24mm