Ok Tibor, no problem. You are doing very interesting things and of course this thread isn't my
thread, everyone can post here. But we shouldn't mix too different things, the forum is big enough to open a new thread.
Now I have extended my turn around scanner with a seat and a back and head rest to be able to do 310° head scans. Just to scan from behind isn't possible because of the wooden slats of the back rest. The person has to lift both feet for a moment when the horizontal aluminium arm is approaching.
Nearly all parts for this extension are from an old kitchen chair. The wooden baseplate of the seat is mounted by a flange on the steel tube of the sunshade pedestal. Because the hight of the seat is constant I had to find a possibility to adapt the hight of the camera and the video projector. This problem was solved by a second square tube plugged into the former aluminium tube. Both aluminium tubes are telescopically adjustable.
Two wheels from an old office chair stabilize the rig against shaking after a turn stop. The minimized head rest is made of an "anatomically" shaped steel wire. And if she or he has long hair it's even possible to comb it over the wire bow so that the sides of the head rest aren't visible after scanning.
The stability of the head rest should be sufficient because this chair isn't a dental treatment chair where the patient attempts to escape from the burr.
Let's see if it works.
Edit: If someone likes to recreate the setup:
Because the vertical steel tube isn't often really exactly vertical, it can happen that the wheels are not always touching the floor when the rig is turned. Therefore it's better not to fix the steel angle at two anchorage points. Means remove the steel angle and use a simple hinge at the horizontal alu arm. On the left side of course.