Making all objects into one solid object for 3D printing

Hello everyone.

New to Sketchup, I currently am using the pro trial version. I finished making my object, and am ready to export to STL for 3D printing.

I have run into a snag. When trying to use the union tool, it tells me that one or more of the objects is either not a solid or is locked. I downloaded ThomThom’s Solid Inspector 3 and I get the Surface Borders error and it tells me that I have to manually close the mesh.

I’m not sure how to do all of that.

The object is 4 individual objects: the box in the middle, and three domes attached to the sides. I need to join all 4 objects to form one solid object, so I can export to STL for 3D printing.

Please help.

Top End Caps.skp (1.2 MB)

so a few quick things:
See how you have a white face and tinted blue face? White is the outside face, and tinted blue is inside face. When doing models for 3d print, you shouldn’t see the inside face.
*This part may depends on printer you’re using:
Your box face has no thickness, so you need to give your box another face to close it off.

Try to image your model is a balloon, will it inflate? Where your dome is intersecting the box, it has a circle face that needs to be deleted.

I’ve merged the domes and box together and deleted the extra faces I mentioned. So now you can see how they’re all one piece with no extra faces. However you still need to close the box.

Top End Caps-2.skp (169.6 KB)

Quantj, thank you for your reply.

I saved your file and looked at it, and am still unable to merge the objects. I understand what you are saying about closing off the box, but the object has to be the way it is. The inside is meant to be open like that.

If I just save the whole thing using the export to STL plugin, will the STL file print the whole object as we see it on screen? What I am asking is do I need to join all the objects together to print the thing?

Also, out of curiosity, how did you hollow out the domes?

Thank you!

I merged the 3 domes with the box already. In your file, they were in groups, you can just explode the groups, intersect with model and then delete the extra faces.
As for the dome, Sketchup doesn’t make real solids, its just faces and inside the shapes it’s hollow, so I deleted the bottom face of the dome.
I’ve never tried printing a face with no thickness, i assume it’ll fail. And I understand that the box has to be like that, but think in physical world, it must have a thickness, even if it’s just 1mm. A face in sketchup has no thickness, so you have to give it one by modelling out both sides of that face. You can google up more details on sketchup and 3d printing as I feel like I’m horrible at explaining this.

Even if you fix all of that…

There are clearly internal ‘flaps’ that you need to delete…
Also you are modeling at a very small scale, so SketchUp might fail to make some tiny edges and their related faces - if the length is < 1/1000"

To make a proper solid from what’s left either make a full 3d object using what you’ve got or use a Plugin like JointPushPull to gibe thicknesses to the faces thus far [note the 1/1000" warning !]

Turn on Hidden Geometry and view the model in Parallel Projection mode, Front View.
There, you’ll notice all three hemispheres are slightly tipped,


Since they’re components, you can rotate and move move them into alignment with the faces of the box.
Correcting tiny misalignments can be a bit prickly.
It may be quicker and easier to simply erase the crooked hemispheres and model new ones.

Once the hemisphere components are properly in place, explode them.
Then, Select All > Context click on the selection > Intersect Faces > With Selection
Now erase the flat bottom of the hemispheres.

Like @quantj says, the sides of the box must have thickness to create a closed volume that when made a single Group or Component it becomes a ‘Solid’.

See this revised copy of the original model:
Top End Caps-Fixed.skp (185.6 KB)

If you leave the box as one component and the hemispheres as three instances of a second component, most 3D slicers will take care of the boolean joins for you. In this case, I started from scratch and created the four components: Top End Caps 15.skp (127.3 KB)

The entity info reports that each is a separate solid. When exported as an STL file, A MakerBot slicer will produce this result:

My favorite 3D printing vendor processes it as well:

This method has an additional benefit in the event you want to change the hemisphere’s radius, shape, position, etc. Since it’s not joined to the rest of the model, this simplifies things greatly when making edits.

One other observation, the explode/join process creates an additional complexity of triangles as can be seen by comparing the STL files:


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Nonetheless, the point was help the OP grasp the concept of Solid, recognize errors and learn from them.

I cant subtract one from another because it says all my objects but one is not solid! is there a way to make it so the other objects are solid?

I’m sure there is but since we can’t see why the object is not solid, there’s no way to tell you for sure how to make it solid. If you’d share the SKP file we could help.

Skp isn’t an option to download.

Why? If you’ve got a SketchUp model and you’ve saved it, there’s a SKP file of it. When you hit Save, a SKP file is created.

its too big to upload on here so you can see it.

Upload it to the 3D Warehouse and share the link.

I uploaded it into 3d warehouse, but I don’t know what link I’m supposed to do.

How about just giving us the exact name of the file as it shows in the Warehouse? I’ll search for it.

Copy what’s in the address bar and paste it into the message box.


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That helps narrow it down.

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I changed the name to soda dispenser fridge