Hello! I use 3d printing for my airplane models for private purposes only, as they are on a weird scale. I’ intend to try my hand at ground vehicles too, I’m curious about how tank tracks will come out, I’ll have to run a test sometime. Careful, I’m still quite new at this 3D business, and I tend to do things the hardest way. Then I find out there’s a plug-in to do exactly that, install it, so next time I forget I have it already and do things the same old way! Nobel Prize material indeed!
Well, back to topic. Following advice I got here, in order to avoid SU’s quirky behaviour with very small dimensions I design my models in quite a larger scale than 1:1, my models are 100x greater than original, so you can imagine a Spitfire 3 times bigger than the Great Pyramid! This may sound crazy to most, but airplanes being so lacking in planes, so full of curves I mean 
, complex intersections may create micro-geometries that may play havoc with SU. So bigger sizes help preclude that.
Most airplanes are symmetrical along the vertical plane so I only have to design half of it (great, he just reinvented the wheel!). The main problem now is that the usual model is a shell with zero-thickness walls, so you have to to provide thickness. So I cut up my fuselage in separate bits as the Shell command sometimes goes goofy with complicated geometries, so I break it up in segments, no big deal there. My usual shell thickness is 1mm in real terms, so on the drawing it will have to be big enough to account for the scale factor.
Wings are another thing. Normally I make a copy of the original wing, downsize it for the thickness in all directions except the wing-span, and then insert it inside the outer surface. This is all fine but interferences with wheel wells tend to be quite tricky. I do shorten up the inner wingspan to leave the sometimes complex wingtip as a full block for simplicity.
There you go for a start. If you’re not all already asleep from reading all this, I am for writing all the nonsense.
Cheers!