Welcome to the next steps :)
After the Stewalin was dry and hard, I searched a fitting socket.
I found one with nice color and stains, so I taped all the areas, where no paint should be.
Then I marked the edges at the Stewalin and used a saw to cut away parts of the wall, to fit it in.
I used my plans to cut out the two sides of the shed, just piercing through the plan, right onto the plasticard.
The wooden beams are 2mm Plasticard strips, the door beams 1 mm. I used the scalpel to scratch in a wooden texture and cut away the edges at some points.
The door section was scratched directly on the shed side, because this makes it bend, I glued some thicker plastic behind it.
Now just glue the sides together and than to the wall.