@Isabelle,
the wheel has a diametre of 72 mm
the base is 58 mm width (as it comes with the kit),
Plus 2*18 mm for the side beams.
I made it 14 mm narrower, keeping the wheel in original size. If I would like it
even more narrow, I could cut the planks for the wheel with only a sharp Scalpel)
The wheel crane can fit good with 30mm figures
if you'll give it a central position in the display.
If you intend to have it rather in the background,
it will be "too heavy".
O.K.
Meanwhile I had to learn, that my way of thinking was wrong:
Winding the rope on the outer wheel would cost too much force from the men in the wheel.
To use it senseful, one has to wind the rope on the wheel's axle / axis.
(the few historic pictures show exacly this)
That means - I have to withdraw my alterations, the width of the whole contraption will rise substantially
and -my rating- the kit ist not suitable for using it with flat figures.
(And this means, that the Reibold figure is technically wrong)
Sorry, Isabelle