As mentioned in the previous note, I had a lot of problems with the stability and balancing, and not even the head was attached! So I just gave up on that design and choose the one used more often by other people – wide base with wheels spread widely.
Construction in this way gives a lot of space under it to have extra weight attached and having the centre of mass situated lower.
There is really nothing special to mention – I just cut the wheel from plywood, cut the holes for wheels and attached them.
As the platform was big enough to fit the loose elements, I gave it a quick test-drive:
Turning in place works – I did not test going forward-backward as there are no rollers in front and back of this base yet, so I would not like the styrofoam to be scratched.
And another one on the floor: