ok the idea with sliding regulated extension is put a way for now and just at simple extension is made. this is also making the rotating in the XY direction out on the monitor vesa mount instead of back on the rail. this makes it possible to slide on the rail to adjust the distance from the rail to the mointor. estimated printing time 3-4 hours.
starting by sketching up in 3d CAD program a adapter plate for the original VESA 100 mounts making them able to be adjustable in and out to compensate for the radius of the rig. problem is that the radius is not made for 5x in portrait
i'm starting whit the depth adjustment feature based on a pipe design to be able to slide in and out on the pipe using a threaded steel rod in the middle for adjustment