What's the difference between modeling for 3D printing, and modeling for video production?

Question

I've been watching a lot of youtube lately, and a lot of modelers are animating, using textures, and making sure light reflects correctly from their models. One uses 8-sided cylinders because his rendering engine will make it round.

I'm interested in Blender strictly for designing models for 3D printing. How does this differ from, say, someone generating photo-realistic lighting-accurate models?

As as example, the boolean modifiers aren't liked by some of the high-end modelers. But for a someone who intends to 3D print, is the union modifier good enough, even though the resulting mesh isn't elegant?

Answer 1

Every 3d printing process usually has its own design guidelines. It all depends on the method of printing, type and model of the 3d printer, materials as well as purpose of the parts or things you wish to print.

In general 3d printing requires objects with closed volume and there are limitations of wall thickness and detail size all depending on the materials and printer you are going to use. You simply cannot print open surfaces that do not define any volume.

Messy geometry like non-manifold geometry, holes, errors with normals(surface direction) will often produce unexpected results.

Normal and bump maps have no meaning at all, displacement needs to be applied.

Smooth shading may be deceiving since 3d printing will output the actual geometry, so if you need some smooth forms they may need to be somewhat denser than what you could get away with modelling for rendering.

All concave and non-planar faces may give you problems, because they will be triangulated in order for them to define a real volume and if you let the software do it for you automatically, it may not cope with it well in all cases.

So generally you need tidy geometry. Boolean operations may introduce problems with that(tidy geometry) so in those cases you need to deal with it. That's a good reason to avoid booleans when possible as with any other kind of modeling. Avoiding does not mean they are not useful in certain cases when you know what to expect and that it isn't going to be a problem - same as with any other kind of modelling.

A lot of 3d printing software(slicers) somewhat cope with intersecting geometry, but you should avoid it when possible and check for possible problems in that software before printing. Again - this depends on the 3d printing process you choose.

It's a good idea to check guidelines provided by your printer's manufacturer.