DIY construction 2 (construction)
Going to Work
Embedding a model into your layout becomes much simpler when it doesn't have a bulky (plastic) base plate. To achieve this, I always attach walls to the sides of the ground floor, rather than placing them on top. This approach, as shown in the drawing, is even more effective when using slightly thicker cardboard.
Start by sketching the floor plan onto your cardboard, ensuring you account for the thickness of the future walls.
Carefully cut out the ground floor and test it in the intended location. This is the perfect time to make adjustments, whether it's resizing or refining your model!

General starting points for self-built models (drawing texts still need to be translated)

Ensure that walls intended for future viewers are designed with minimal seams at their corners for a cleaner, more cohesive appearance. (drawing texts still need to be translated)
Inner walls
If you're planning to include rooms in your model, such as for lighting purposes, now is the perfect time to add the interior walls. Keep in mind that these walls should be placed on top of the ground plate and therefor must be lower than the outer walls.
The next step involves adding an additional storey. This floor must fit precisely within the existing outer walls to ensure proper alignment.
The final piece is the roof. For flat roofs, they are typically the same size as the ground floor. You can use the ground floor layout as a reference or template. However, keep in mind that the roof rests on top of the outer walls, so there’s no need to subtract the wall thickness when planning the roof dimensions.
To keep the roof securely in place atop the walls, add a smaller layer of cardboard to the underside of the roof. This additional layer should align neatly within the outer walls for proper support.
Not only does this extra layer provide stability, but it also makes the roof more durable. To conserve cardboard, you can use narrow strips along the edges, positioned directly against the outer walls. This will further help prevent light from seeping through the seams.
Outer walls
Next, sketch the outer walls onto the cardboard. Ensure the side walls are slightly shorter by the thickness of the cardboard on one side, as the front wall will overlap and sit in front of them.
The backwall should be reduced at both ends, because here both side walls will overlap. Ensure that walls that will be in full view have minimal seams at their corners.
Avoid cutting large holes in the walls for doors and windows just yet. Instead, sketch their placement on the cardboard. Once that's done, cut out all the walls and ensure they align properly with the floor. Use painter's tape to temporarily assemble the walls and floor together for a quick check.
Attention: Even painter's tape can damage cardboard surfaces. To reduce its stickiness, press the tape onto a piece of clothing, like a pullover, before applying it to the cardboard. This helps minimize potential damage.

If everything fits, the model can be disassembled again. Be sure to mark each piece as needed to indicate its correct position. Clearly label the top, bottom, inside, and outside sections as well. This will help ensure that elements like windows and doors are later placed correctly.