Possibly essential information needed to answer this question:
-The stool consists of one part, it is not an assembly.
-I created the main shape using a swept boss/base. Then I used the 'slice' function to create a certain amount of sketches within the swept boss/base. I extruded these sketches one by one. I finally added an extruded boss/base on the side and created a linear pattern to get the same result on the other side of the stool.