Create walls for organically shaped objects for 3d printing

I am a longtime user of SketchUp but cancelled my subscription when I retired a couple years ago. I am now interested in 3d printing sculpture and starting to research. I will start with rectilinear objects with which I can confidently create solid objects with the necessary 3 or 5 cm walls. However, it is not yet clear to me how to create walls for organically shaped objects. Can anyone offer advice or point me in the right direction?

It depends a great deal on what the exact shape is but it might be as simple as making a slightly scaled down copy of surface inside. Or you might not need to worry about it since the slicer will give the walls thickness based on the settings you use.

This clearly isn’t an organic shape but you can see in the section cut there’s no thickness to the walls. (5% infill so the wall thickness is easier to see.)


The slicer has added the wall thickness per the settings.

You may be able to use Fredo Joint Push Pull Thickener depending on how you’ve built your model.

Thank you for the quick reply. Ill keep that in mind as I progress. Is the slicer the SketchUp file export for the 3d printer?

The slicer is an application used to take the .stl file you export from SketchUp, apply the appropriate settings flow rate, nozzle temp, etc.) for the print media and things like infill density and support density and then save out a G-code file that the printer uses to make the object.

And you’re welcome.

Wow, I’m learning more. Thanks. I was thinking of using a print service such as i.materialise at least initially so I don’t need to invest in my own 3d printer.

Thank you. At this point I don’t even know what the Fredo Joint Push Pull Thickener is! Ill look it up.

A 3D print service can be a good option until you figure out what you want to buy for a printer. You would then download a .stl file from SketchUp and send it to the service. They will make the settings for wall thickness, infill, support, etc.

Joint Push/Pull is an extension for SketchUp available from Sketchucation. It can be very useful in some cases but again, it depends on exactly what you are modeling and what you need. If you are modeling something like a bottle in which you need an interior hollow space, you would need to create inner and outer surfaces. The object in my screen shots as inner and outer surfaces for the holes through the piece, for example. Joint Push/Pull wouldn’t have been suitable for those surfaces but it could be in some instances.

Gee. That would be great, but I thought I read somewhere on SketchUp tips to be sure the walls had thickness. i.materialise provides minimum thickness for each material.

It depends on what you are modeling. A bowl, for instance, would need inner and outer surfaces in order to be 3D printable. If you remember from before, faces in SketchUp have front and back sides and no thickness. As far as 3D printing goes, the front faces point toward air and the back faces (green in my screenshot, above) face the print media.

I suggest you define organic, as SU really isn’t the best solution for complex truly organic shapes.

This is a huge help for me to know this! Thank you.

By organic shape I mean anything that is not rectilinear.

Since I am just starting to learn about 3d printing, I will start with SketchUp since I am familiar with it. Over time I may need other software. I know there are many options, but at this point I have no idea which one I would use. Any suggestions?

FWIW, when I model for 3D printing I set model units to meters and create my model as if millimeters are meters. Here’s an example.

Here are the components as modeled in SketchUp.

The .stl was exported from SketchUp with units set to meters and it imports into the slicer in millimeters.

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Very nice! What material do you use? What type of printer?

I am not sure if i.materialise printing service will automatically convert from m to mm. If not I can always do it manually.

Thank you. The U-joint is just PLA. I have a Creality CR-M4 printer which works well but if I was looking for one now I’d probably go with a Bambu Carbon X1 although it’s a little on the small side.

When you upload the file to i.materialise you have to specify the units as either millimeters or inches. By their nature, .stl files are unitless so you don’t need to scale down if the export units were meters and you want millimeters.

Export Options


i.materialise upload page.

U-joint .stl uploadeded.

Ignoring the cost of the printer, it’s a whole lot less expensive to print this at home.

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I am testing capabilities of SU Go. I intersected two cylinders of different diameters. Seemed fine until I used the solid inspector and got the following message (see screenshot attached)

Circled is what I assume are the “short edges”. I scaled my model up and the radius is 400 m and 119.2 m. Does this mean that it would be impossible to 3d print intersecting cylinders of differing diameters?

Short edges acan be an issue but how does Entity Info identify the object? How large is the object? With what units are you creating the model?

I redid the intersection and it works! I started a new sheet in meters (before I had changed it from mm to m) with 48 sided cylinders (before 96 and 24 sided) at 100m and 40m diameters (before 800m and 240m radius). The key I guess is always to START in meters. This seems like its going to be a trial and error process, but are there any other guidelines to follow? Thanks for your guidance!

This is what I’ve found to be a good start when I model for 3D printing. If I know the dimensions of the object in millimeters I just model as if millimeters are meters. If what I have for dimensions is inches I model as if inches are meters and then I do scale up by 25.4 before exporting the .stl because the slicer I use only works in Millimeters. I modeled this last night and it’s just about to come off the printer now.

Reducing the number of sides on the circles to 48 might not hurt anything. I usually use 96 sides for most circles when I model for 3D printing. Working at the larger scale from the beginning will help to avoid that Short Edges message. That message on its own doesn’t really indicate an error. The object can still be 3D printable. That message is helpful because it lets you know there’s some small edges that might develop into problems if you do further operations to the model.

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