To create a niche in a wall in your design, you can use the following steps:
Select the wall in which you want to create the niche.
In the design panel, locate the "Tiling and Cutting" tool.
Click on the "Tiling and Cutting" tool to enter the drafting portal, where you can add a shape to create the niche.
Select the "Add Shape" option within the drafting portal.
Choose a drawing tool, such as the line tool, and use it to enclose the shape of the cutout you want to create.
Click "Apply" to create the shape.
Select the created shape within the drafting portal, and in the properties section, assign the property "Cut" to the shape. This property defines that the shape will act as a cutout in the wall.
Specify the depth of the cutout. In your case, if the wall's depth is 150mm, you can set the cutout depth to be less.
Select the desired material for the niche from the Material drop down menu or from Fetch from Store.
After configuring the depth, return to your drafting portal.
You will now see that the cutout has been created in the wall, allowing you to customize your design with wall niches as needed.
By following these steps, you can easily add niches to your walls in your design project.