I got some parts from an old military device. The axis is 150mm in diameter and aprox. 1 meter long. The base is made of a 10mm steel plate. A stand of steel profiles is welded on top.
Right picture shows the polar axis attached to the base.
The altitude of the axis can be adjusted with a skrew in the low end. To adjust in azimuth I'll have to move the hole base. Oval holes in the base plate make this possible. The driving disc is attached. The disc is 80cm in diameter and is made of a 20mm thick steel plate.