@ntxdave Thanks Dave. A lot of tedious work and trial and error and my imagination. Started using outside assets since I figured that I can't or don't need to model everything. In this case I saw the sample image and started with a simple Sketchup component for the ceiling and went from there.
Lots of Profile Builder 3 moulding. For the stairs I started with a spiral staircase base made using 1001bit tools. Countless hours later I came up with the (almost) final stairs on the right. I used Fredo's Curviloft for the outer stringer as well as Fredo's bezier tools as well as Profile Builder 3 for some details and the handrails. The balusters were found at 3D Warehouse.
So imagination, knowing basic carpentry or architectural sizes, using Sketchup tools and experimenting, using assets, a lot of tedious work and trying to not call into the perfectionist trap. That and a lot of bugsplats.
Forgot to mention that solids don't have to be perfect solids. You can't notice any little bugs in the rendering.
