Thanks
Next step was of course the hull. I took the same way - I turned the standard squeleton structure of the original model into a box.
The serious problem I had was the working suspension - how to build a system of springs and keep the space inside hull for engine, turet basket etc?
The only way was to have working torsion bars.
As a picture is worth a hundred words - I shown my solution on fitst photo (the strange stuff inside the spring is copper grease).
A bit later I found out that the springs are not strong enough and I had to immobilise some suspension elements, but it's another story...