As mentioned in 11.3.1 Why Use 3D Boxes?, Inkscape’s 3D Box tool is not intended to be a replacement for specialized 3D design applications. Inkscape is a drawing program—and as such, its 3D Box tool is best used as a drawing aid. This is what we’ll try to do in this simple tutorial.
A “3D-correct” drawing is simply one that satisfies the rules of perspective drawing which have been well known to artists for many centuries. It does not need to exhibit perfectly realistic shading and texturing; it just has to get its lines and objects approximately correct with regard to angles and dimensions.
Granted, some styles of drawing do not even need to have correct perspective; sometimes, intentional perspective distortions may have an artistic value of its own. Many artists have a knack for drawing 3D-correct art without using any technical aids. However, quite often you will notice perspective errors, ranging from barely noticeable to embarrassing, in pieces of art which would definitely do better without them. I think, therefore, that many artists—not only the beginners—would appreciate a quick and easy way to set up the perspective for a drawing without tedious manual measurements and helper lines. Let’s see how this task can be approached in Inkscape.