While going through the process of making a 3d model and then printing it, I learned a lot of things that I thought could be useful for those of you who want to give it a try!
So, here are some tips & tricks that will save you some headaches while you’re at it:
1.- PlanningThat is, planning for 3d printing. This is different from planning for 3d modeling, because some severe restrictions apply.
First, you should go to a website that provides 3d printing service, and look for the materials that they offer; Each material has its own price per cm3, as well as different setup costs. Choose your material and have a look at its properties; depending on the material you choose, you’ll face some limitations like “minimum wall thickness must be 3mm”, or “maximum size must be 30cm”, for example.
The difficult part is keeping your model between those boundaries, specially the “minimum thickness” one. For example, a “mimimum wall thickness” of 3mm means that no single piece of your object can be any smaller than that, mainly because it could easily break into pieces.
Usually, you can have details smaller than the “min. wall thickness” value, but be careful: details, that excludes any part that supports weight. There is a thin line separating the concept of “wall” and “detail”. Imagin a character for example; legs and arms must respect the minimum wall thickness because those are supporting parts, they hold weight. Other features like nose, mouth, pockets, etc are considered details because are not intended to sustain the object, so can be printed usually much smaller without troubles.
Once you have decided which material you’re aiming for, and you have in mind the limitations of that material, you are ready to go to the next step.
2.- ModelingI assume you know how to model, otherwise you wouldn’t be reading this. Just remember to model in scale to the final size you’re pretending to print the object. If your modeling application supports it, it’s a good idea to take some measures here and there from time to time to be sure that you meet material specifications.
Also, and this is a very important tip, you have to hollow your object! This is important because 3d printing price is volume dependant, so if you hollow your object you’ll cut the costs down. If your object is not very complex, a simple inward extrusion will do the job. Remember to reverse the normals of the inner faces now, as they should be facing outwards not inwards (weird for a 3d modeler, I know, but that’s how it works).
Hollowing your object is a time consuming process, because you’ll have to keep the extrusion to a minimum wall thickness value across the whole object. But you’ll end up with a much cheaper object! If you find it difficult to hollow some parts, do it just on the bigger ones (as they are going to be the ones that take more material to build!).
Also (depending on the material you decide to use), you’ll have to perform a small hole in your object so the building material can later find its way out.
Using several meshes (or “shells”, that is: several pieces) seems to be fine as long as they get combined into a single mesh at the end of the modeling process.
Lastly: Keep in mind that you’re building an object that is going to be converted into a real thing. So, if it doesn’t hold by itself (maybe its center of gravity it’s not right), or you think it may fall, a simple trick is adding a platform under your object.
3.- ExportingThere are some 3d printing companies that accept collada, or obj files. Even some accept .ztl straight from zbrush. But the standard, which all companies will accept, is .stl file format.
If your modeling application does not support .stl exporting, you’ll have to export it as .obj and then use a software like MeshLab (open source) to open it and re-export it to .stl
Don’t forget to triangulate your object before exporting!
I used Maya as my modeling software, and it doesn’t export to .stl but I found an awesome free plugin called MultiTool by Ticket01. I’ve contacted the author to check that this plugin could be used to this purpose and he said that it was perfectly fine (the statement of non-comercial on his website refers to “this is a non-commercial software”, that is, “free” – and does NOT refer to a restrictive use; this has been stated by the author via email). So if you’re using Maya and you need to export to .stl as well, download the plugin and donate some bucks to this guy, he truly deserves it!
4.- Final checkingsNow it’s time to check for watertight meshes, correct normals, and so on. You can use several programs to do that, I recommend you MeshLab (open source) and NetFabb Studio Basic(free)
Within NetFabb you can check for wall thickness, view object volume, slice parts, perform checkings, and much more. It’s a great free app for this purpose!
Finish!That’s all! Now your model is ready to be printed! Remember to be patient through the process of revising and correcting mesh errors, I had to rebuild some parts of my object several times, so planning in advice what are you aiming for is a very good idea.
Hope this helps you in the process of 3d printing your model!
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Great, but i think shelling the model is not hard at all. In 3ds Max, you can apply the ’’shell’’ modifier to your model to obtain a shell of the desired thickness.
Really cool tips, thank you for pointing all the sensitive cases out. Would be so useful if i ever print a model.
Reads like instructions for Shapeways
Reads like instructions for ShapewaysDuann
Yes, that’s because I printed my model there!