How to solidify 3D design after punching hole in it? Need it for 3D printing

Hi all,

Having trouble solidifying a 3D design after I punched a hole in it using the plugin VisuHole. The " inside" of the design is open, so I have to close it up. Which I did. However, when I group the design, it says its a Group and not a Solid Group anymore.

I have used the plugin CleanUp to solidify the design in the first place, then punch a hole in it. Then closed up the inside. However, no luck getting it back into a Solid. Using CleanUp does not do it. If I can, I could upload the file.

Any help or tips for the direction I need to look into would make me so happy. I am autodidact and usually able to solve issues by using YouTube and forums, however I feel stuck on this one for for several hours now :slight_smile: I believe it is possible to solve it though.

Thank you so much for reading this and considering to help me out! Happy with any tips.


Share the .skp file so we can see exactly what you’ve got and so we don’t have to guess at the steps you’ll need to repair the object to make it solid.

PS. I have used other methods too such as:

  • Intersect Faces > With Model
  • Tools > Solid Tools > Substract

Unfortunately, the problem with Intersect Faces was that I could not delete the cylinder I used to punch a hole “perfectly”. I think the problem is that my model has a curved face.

The problem with Substract was that half of the model suddenly disappeared and I would not see a hole at all.

Sorry here is the file

Letter O for forum.skp (424.5 KB)

PS 2. Just to clarify. The model is basically the letter O in 3D, however it has a flat surface. I then duplicated this and mirrored it in order to make a letter O fully in 3D (so without a flat surface).

I then solidified the 3D letter O > Solidified it using CleanUp > Punched hole in it using Visuhole > Closed up inside of model for 3D printing > Could not Solidify model after grouping it.

So you want something like this?

First, you should scale the model up by 10x or 100x to avoid creating tiny faces. Also make sure the O object is a solid group. Then make a cylinder which is also a solid object. Then you can use the Subtract from the Solid Tools to create the hole.

The way you made the other one using Intersect Faces didn’t work because you didn’t leave any of the faces from the cylinder inside the group.

Wauw that’s so fast haha! Yes that’s exactly what I need. I will try out what you suggested and if I can recreate it, I will be so happy. Just need to do 25 more after the letter O is done successfully. Thank you for your quick reply!

Is yours a Solid Group again by the way?

You’re welcome.

How will these be used once you have them printed?


One thing I find useful when modeling for 3D printing is to work with the units set to meters. Enter millimeters as meters. When you export the .stl file make sure units are also set to meters. When you import into the slicer using millimeters the model should be the correct size.

Here’s an example I printed. As you can see the model is quite large. In this case I wanted these clips to be 1 in wide and they clip onto 1 in. diameter tube.

And the 3D printed clips installed.

Hm. Mine’s it not a Solid. I think its because on one side its still open on the inside. I need a 23 mm hole so I will make the letter O slightly bigger so it won’t leave any open areas.

I want to use the 3D printed letters to make a silicone mold for candle making. I want to be able to slide letters over a LED taper candle. I want to try a small candle business eventually selling customizable sets. E.g. for a baby shower or children room interior decorating item.

Thanks for the tip, I will set the units to meter and double check if its correct before printing. Never printed anything ever before let along designed for 3D printing. I want to use a 3D printing service.

Looks like your cylinder is drawn off center.

Yes, that’s what I thought, good to know you think that’s the issue too.

So you design your model in meters so you don’t have to enlarge the model to avoid problems? But then when you import the file into the 3D printer you have to make sure you change the model units from meters to millimeters? Or is that something you do on the 3D printer?

Yes. This helps to avoid issues with tiny faces. It also lets me create smooth curved surfaces.

No. The .stl files are exported with Meters as the units so they match what was used when I model the thing. The .stl files have no units. The slicer will take them usually with millimeters as the units (some slicers can import as inches, though) so the parts end up being the right size without having to resize the model in SketchUp or any other gymnastics.

Thank you, this information is very useful for my next steps as I did not know this :blush: Have a great day!

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