Making a Solid for 3d Printing

Hey forum,

I am a total noobie so I apologize up front. My neighbor asked if I could 3D print a part for an old car he is restoring as he can’t find a replacement part. Unfortunately, I had to try to design the part and Sketchup was the only tool I could find to do it in. I believe I have the shape correct but it is hollow and for the LIFE of me, I can’t figure out how to make it a solid. Can someone help?



PS - The object file can be downloaded here: ShareFile

SketchUp is a surface modeler. That is, it portrays the “skin” of a solid, with nothing inside. This is perfectly adequate for 3D printing though. The main thing is to select the object and make sure that SketchUp’s Entity Info window reports it to be a solid.

Edit: I got your file. It has several issues.

First among these is that in SketchUp a solid must be a group or component. Your model is all ungrouped edges and faces.

Once it is made a component, there are some lesser issues to correct. There are some stray edges (ones not needed to define the surface) and some reversed faces. These are easily fixed, at which point the object is reported to be a solid.

Here you go, I oriented the faces, all white on the outside and removed a few stray edges, then made it a group.
No need for a share site for such a small model.
Mitches Part 3-8-21Fixed.skp (206.9 KB)


Mitches Part 3-8-21.skp (166.1 KB)

I did the same things Box did and a little more cleanup.

Wow, I wrote hoping that in a few days someone could point me in the right direction… Never thought someone would respond so quick and be so complete!! Thanks a ton! I will send this to the Makerbot tonight and see how we did!!


Dave, sorry to bother which such BASIC questions and I honestly will keep trying to solve myself but… The print came out great. I just need to make some adjustments now. But, trying to do so and even when I set it to Edit Component, I can’t push/pull curved or smoothed faces. What do I have to do to edit it then return it back to this state?



Pushpull works only on a single face. Curves and smoothed surfaces are made up of more than one face. If you view->hidden geometry you can see the individual faces to pushpull them, but that might not accomplish what you wanted…

Push/Pull only works on single faces. It might be that turning on Hidden Geometry will allow you to access the faces you need. Or you may need to do something else. It depends on the exact changes you need to make.

Is that something restricted to the full (locally installed) app? I looked through all menu options in the web version and I can’t see anything related to Hidden Geometry… What I need to do is simple but as I recall, the surface I am looking to modify was two pieces before but with DaveR’s changes, shows as one surface…

No. Look in the Display panel.

Thanks Dave, that was what I was not finding. With that I was able to extend a portion of that side rail.

Interestingly, the left side I was able to extend as a single push/pull. The right side I was only able to extend part of it. The right hand section is non-responsive to push/pull. The tops and back are but not the front.

What is locking that face?

Once I get this, there are two more changes I need to make to match the original part from his 36 Oldsmobile. That is: Make the top edge curved (top of that portion X’d in my screen shot) and make the notch in the middle section a beveled curve. Care to point me in the right direction for THOSE changes? :wink:

Thanks again to all of you for being so patient and helpful!


There is a slight corner in the top edge where the hidden line meets it:

Screen Shot 2021-03-09 at 9.08.02 AM

As a result, pushpulling either portion puts its extrusion in the way of pushpulling the other one. Because that bend is so slight, I suspect it is not intended. If I’m right, you can edit that portion to correct it.

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I had to step away from the computer but it looks like Steve has got you sorted on that. It’s important to make sure that you keep edges on axis while you are modeling. Another thing to watch for is radii that aren’t tangent to the edges they are connected to. For example the selected curve here shows that.

Not sure what I did to change my view but I cannot replicate what slbaumgartner showed.

So, I find it impossible to fix! ARGH…

Dave, are you referring to the lines under the yellow that extend outside the guidelines? I was hoping the radius would SNAP to that line… Apparently not!

oooh, oooh, oooh - I think I am learning!! I selected that face, then right clicked and Aligned Axis. Now I can push/pull!!!

Nope, NOT learning. I can extend one or the other faces but not both. Must still have an angle there that I can’t see… Sorry guys!

OK, I think I got it. I took the side I COULD stretch, made a group out of just that side, copied and inverted it, then replaced the wonky one with this new side. It is printing now. Hoping for the best.

I created a guide line using the tape measure tool and double clicking on the other part of the edge. Then when I zoomed in I could see the gap. The guide also gave me an intersection with the side where the crooked part would need to go.

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That is a great method for finding an issue like that. I will remember it. Now to figure out how to know I need to before pinging you all!!

My test print is looking good though. Thanks for all your help - Each of you!

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FWIW, figuring out a good, clean workflow is key to making things like this simple and easy to model. I know you have changed the model since the file you shared earlier but, here’s a little thing I whipped up to show the process I would use to model your part. With this process there’s never a point where I end up with internal faces, holes, or stray edges that would prevent the thing from being 3D printable. Nor do I have any reversed faces at least after the thing first becomes 3D. Note: since this is symmetrical I certainly could have modeled only half of it, copied that geometry, flipped it, and joined it to the first half. But where’s the adventure in that? :wink:

Mitches Part 3-8-21.skp (141.6 KB)

  • I outlined the largest surface first. It’s the thing the other features get added to but notice those features are not drawn in yet.
  • Give the large surface thickness.
  • Then start adding the features. Offset makes quick work of outlining the flange on the bottom and then Push/Pull creates the flange.
  • Outline the feature on the top surface.
  • Extrude the top feature only up to the height of sloped sides. Draw in edges to divide the top face of the feature so there taller part can be extruded with Push/Pull.
  • Use Push/Pull to pull the face up to the full height. Select the edges across the ends of that top feature and use Move to move them down to the larger face.
  • Make a component/group and check to see that it reports as solid.
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