Next up, let’s add some furniture—for example, a sofa.
In creating 3D box compositions, it is convenient to use snapping (7.3 Snapping) so that boxes align precisely. Open the Document Properties dialog (
) and, on the Snap tab, enable both Snap to paths and Snap to nodes.
Now, draw a smaller box inside the larger one. (We don’t need to worry about z-order of the boxes; their default style uses partial transparency so you can always see the edges of all boxes you created.) Note that the new box uses the same perspective (i.e., the same vanishing points) as the room box. Grab its lower left X/Y handle and drag it so it snaps to the lower left Z-edge of the room. That will be the foundation of the sofa; use the other corner handles to give it correct height, width, and depth:
For the back of the sofa, you can draw a new box and snap it into alignment in a similar way; or, more easily, you can duplicate the sofa base (
) and drag its X/Y handles to resize it into the correct shape:
Now, assuming this is a basement, let’s place two small basement windows on both sides of the sofa. A couple of boxes flattened in the X dimension will make perfect windows. However, how do we properly place them, given that no side of a window aligns with a side of any other box?
Again, the duplicate-then-resize trick is the easiest way to achieve this. Duplicate the largest box you have (i.e., the room itself); 
-drag its front X/Y handle backward (along the X axis) to squeeze it into a thin layer; then, drag four handles on the X/Y plane to resize the window into place. For a second window, just duplicate the first one and 
-drag its central handle in the Z direction; this way, the second window will be an exact perspective-aligned copy of the first one. Using the same duplicate and flatten trick, add a doorway box on the Z-most wall (i.e., the wall closest to the Z vanishing point), so that it protrudes outside of the room box:
