3D modelling is both a professional occupation and a hobby for me.
I use 3D models extensively in HW designs for modelling electronic components. This way I can verify if my PCB designs are correct, create realistic images of the boards for my customers, and allow mechanical designers to insert the board into the 3D model of the final product, and see how it fits. It is especially important in space constrained environments, like tools, machines and robots.
While it is possible to adjust the offset and orientation of the models in Altium Designer, it makes life easier if the models sit on the XY plane, and their origin is at the center of the component. Internal details are not so important, but the boundary must include maximum tolerances.
I love regular, and not so regular, polyhedra.
I created the first models while I was a child, out of paper, wires or wood. Nowadays I prefer SolidWorks to make virtual models, although occasionally I still assemble some out of real materials.