you could try checking this project file:

Counter-tut.sh3d


Create a level @88 cm ( or at whatever height your preferred counter might be) :



Draw your counter with the [font=courier new]Create rooms[/font] - tool

Modify your sink:



Configuring an object as a staircase, it will always make a cut-out in any floor or ceiling.

Study the project file. There are several ways to do this.








Cecilia