Sorry about this, but I think you are mixing two incompatible concepts: a diagram and a 3D model. In my opinion, a diagram is an inherently 2D presentation; it is not intended to be to scale or necesssarily even to look like the real thing it is depicting. It is not intended to be representational, but to show functional relationships between elements of a system and perhaps a processing sequence. I don’t want to be too specific about what a diagram does because they are so versatile, but I don’t think that adding the requirement that it must be a free-standing object adds much to its utility and probably interferes with its main purpose. Also, consider: a big part of diagrams, generally, is labels, since the elements of a diagram are more symbolic than representational and require a good deal of explanation. How do you plan to handle labels?
There’s no way that what you have depicted there will print out as “1 structurally sound unit.” If it is able to print at all, it will be as spindly and fragile as a mobile, and will probably end up in a heap by the end of the day. You’d need the interconnecting lines to be wide flange beams.
A diagram is a convenient way to present a conceptual view of a system. Its virtue lies in simplifying and abstracting a complicated system and presenting it in a convenient form that can be handled and comprehended easily.