How to get smoother surfaces and merge material together in a good way?

Hello, I worked with this tutorial and generated this: (17.2 KB)

I wanted to print this with a 3D printer from the university where I study, but my advisor told me that there are some mistakes that need to be fixed.

In detail, the mistakes are:

  1. Generally, the surfaces are not smooth, it always seems to have some edges. How can I increase or smooth the subdivisions?

  2. I would like to have some “weird” shapes. But if material goes into other material it seems to be an issue for the 3D printer, and additionally the crossings are not smooth, they look quite buggy. What is the best way to merge them together in a better way?

Does anyone have recommendations for the export for the 3D printer?

Thank you!

Hello Peck,

You are into fairly problematic geometry - you will need to look into meshes for this, to make this geometry in NURBS would create an object of unnecessary complexity (which would also be redundant since you’ll be converting it to a mesh of some kind for fabrication anyway)

Weaverbird will be your friend with 3D printing as it will allow you different ways of smoothing and subdividing geometry - however the self intersections will still be problematic as they make it difficult to calculate what is internal/external (this causes problems with booleans/rendering/printing) - this is where geometry wrappers like Dendro and Cocoon are very useful - I’ve included various things to think about in your file, you may need to feed your Rhino a little bit. (Some of the more computationally intensive methods are disabled, as you enable them, give them a little time to calculate [time will depend on the specs of your machine]) (36.3 KB)

Good luck and have fun!


You are closer than you think! I made a small update to your GH file, exported the result as an STL file, fixed the meshing errors Rhino produced, and got it ready for printing. My printer is fairly large, but I had to scale your geometry down to 25% so it would fit on my printer. Here’s a screenshot of the geometry sliced with PrusaSlicer and ready for printing:

And here’s another screenshot showing more detail of how the slicer processed the file:

Some notes about what I did - and what you’ll have to do to make your print:

  1. The final geometry is made from3 parts: your Loft, it’s offset, and the ruled surface that connects the 2. The result should be a closed Brep, but it isn’t. This is a common problem with Rhino that can sometimes be fixed by decreasing Rhino’s tolerances, but I don’t like messing with this (it’s a trial & error process) so I just create an STL export and deal with it in the slicer.

  2. The STL file that Rhino creates will load into a slicer, but with a boatload of errors. These errors are mesh errors (an STL file is just another kind of mesh), so Artstep’s comments about software that deals with meshes is certainly one way to deal with this. I prefer the brute force method, which is to let the slicer fix the STL’s errors using the Netfabb software. PrusaSlicer does this all by itself and it only takes a a couple of minutes.

  3. Even though the result from PrusaSlicer looks good (because it is) it won’t print properly because there is insufficient contact with the printer’s build plate. This means the part won’t stick to the build surface, and once it gets loose the print is destroyed.

There are a couple of ways to fix this. You can whack off the bottom of the geometry so it has more surface contact area, or you can embed the whole thing in some sort of base geometry. For your shape I’d probably go with option #2.

  1. I changed the offset value to 4 (4 mm in my case), but that was before I realized how big the part is. Scaling it down to 25% means the result will be 1 mm thick, which is not thick enough for the real world. In general I don’t print things thinner than 3 mm or so, so depending on the size you end up printing you should tweak the offset value accordingly.

You’ve made an interesting shape and I’ll probably make a print myself - but somewhat smaller than the 25% version. PrusaSlicer says that size, with no base, will print in a bit over 7 hours. I’m thinking a print about half that size would look pretty nice.

Edit: After looking at the shape in various rotated views it became clear that to print it on a standard FDM printer would require lots of support material. This is because there are lots of places where there are so-called overhangs that an FDM printer can’t print without supports. (Unless it is in a zero G environment.) Support material is not only tricky to deal with, but would mess up the surfaces where it attaches to the main geometry. I tried to find an orientation where supports wouldn’t be required - but I don’t think there is one.

But all is not lost! If you have access to a resin printer you could print this OK. Most resin printers are fairly small though. Or you could farm it out to one of the suppliers of metal prints. These places are quite expensive, but your geometry would look great in stainless steel. (21.6 KB)


Amazing! Thanks a lot!