I was putting this one off as I could not imagine how to start with it, but then a friend commented on the sketch, that she liked the look of it, so I got the motivation to try my hand at it. Actually it turned out the process was quite straight forward, at least with the skill set and methods I have developed.
This is also when I decided I would add a Fillwork version next to the Linework link. Linework is the same as before, only the main geometry lines, while Fillwork is everything but the lines! Check it out! Some figures surely look nice without the lines, but as can be seen in this one some surfaces melt together when the lines are missing, which is why I keep the lines for the main image I post.
The four levels form a flight of steps, but if you take a closer look, you notice that the platform in the back is also connected directly to the platform at the very front, same with the second to furthest away platform.