How do i create this interesting tower with staircase inside?

Wanted to create the tower at 9m high and the staircase, tread = 1500mm and riser = 150mm. And the entrance at first floor and the top. How do i replicate that design?

One method…

ah yes that method, but how do I make the lines to have thickness? And what is the ffd extension?

Basics of SketchUp at