You can try extensions such as TIG's Solid Solver and ThomThom's Solid Inspector2 and CleanUp3 however if your model is as much of mess as you imply, they will likely not be able to fix everything. Probably there will be things that will require human decision making to repair. It doesn't help you now but if you know that a 3D printed model will be required it would be best to model that in mind from the beginning making sure that all bottom groups and components are reported as solids. Solid groups and components tend to be cleaner and are easier to work on so there's additional benefits to making solids from the beginning. You don't have to collect all of the groups and components into a single solid for printing, either. As long as all of the objects are solids, it should print fine.

One thing I find useful is to set the model units to meters and model in either inches or millimeters as needed. So if I need something to be 6mm long, I model it at 6m long. Since .stl files are unitless modeling in meters is not a problem. Export the .stl file in meters (model units) and import it into the slicer software as millimeters or inches as appropriate. Working in meters will allow you to increase the number of sides for circles and arcs. Keep in mind there's no point in overdoing the number of sides you choose. Example: This was modeled at 63.5 meters tall. Imported into the slicer at millimeters and presto! [image: RzlG_Screenshot-1_13_20201_12_09PM.png] By the way, your profile says you are using SketchUp 2019 Make which does not exist. Which version are you really using? That information is useful to those who would try to help you with your questions.

It worked quite well thank you very much. I kne the +/- was good for both plus and minus somehow Hope all is well! [image: W2MB_Capture.PNG] [image: rpm1_Capture2.PNG]

@dave r said: Hard to say exactly without seeing the .stl files you are starting with. Very likely it is a small size/tiny face issue. You might be able to get around it by setting the import units to meters before importing. By their nature, .stl files will have lots of shorter edges due to the triangulated nature of the file so you get to deal with that. Right after I posted, I figured out there's a way under options to change the units from mm to meters when importing an stl. I did a quick test and 2 of 3 models imported as solids... thanks for the feedback

I'll take a look, but well, I did manage to come up with something relatively decent (although it was a relatively simple model, a basic miniature house for a model train exposition)

That's good to know that can be an issue. For this file, I don't see any reversed faces.

Could you show how it looks like now? Is it already hollow, but too thin?

Are you asking for a half mold? Anyway if you have a solid and a you put it in a larger cube... Reverse the faces and you have a "negative object". But perhaps you want half molds--which it seems are needed to print. Then you can put a plane down the middle of the object and the cube and intersect faces. Depending on your shape this can be simple or it can require more planning and knowledge. For printing the shape has to be solid and a clean, solid original shape should lend itself to being a mold. I'm just saying it shouldn't be a trick or require special tools. The shape is the mold itself, you just have to show where the mold material is around it.

I also kind of needed the answer.

Hey Ballbearing, Thank you for the solution.

@tig said: Scaling up to avoid faceting and other small visible geometry issues is a well known workaround. The guys who developed Flowify devised and use this method to model classical columns in the minutest detail - they are miles high in the SKP ! Because you are incorporating complex 3d geometry into the form then the suggested 3d-gives-true-circles in a CAD file export etc is of no use - it's only useful if the geometry is 'flat' - e.g. for 2d CNC cutting... Sorry to beat this dead horse but I am still trying to establish a go forward plan. 1: Is there another CAD program that could smooth Sketchup 3-D shapes for use with a CNC? 2: I have not used any other CAD programs so if Sketchup can not provide what I want what are some easily learned CAD programs that will provide a smooth complex 3-D surface? Thank you for your reply's.

Unfortunately your SketchUp model is NOT a manifold solid. To successfully 3d-print such a form it should be. See the attached image from SolidInspector² which list hundreds of issues [once the geometry - excluding the loose edge near the origin is grouped]. A 'solid' is a group/component which contains just edges and faces, and where every edge supports exactly two faces. So that means no nested containers like groups [you have 70], no faceless edges, no faces with just one edge [you have several] - like shelves, flaps and holes, no internal partitions where a edge would have three or more faces, no otherwise solid forms sharing an edge [with four faces], and finally no self-intersecting forms which might still report as 'solid' but which cannot be 3d-printed. I'm afraid you need a lot of manual fixing of this model. It cannot be 'automated', because the issues are so convoluted... [image: klN0_Capture.PNG]

There is a little trick with VisuHole! For letters who don't work as aspected (here the "R" add a little hole and erase it at the end! [image: bigre.jpg]

@pilou said: Inflate Components by Sdmitch ? Not sure that is you want exactly.. (Zip it and rename .zip in .rbz) Thanks! I'll give it a try...

If you expect the circular holes to penetrate into the form, then you need to draw over an edge in the circle to form a face, and PushPull that into the form by the desired dim, to make a recessed cylindrical hole. If you want a hole to punch completely through the form, then PushPull it more so it is completely through the form. Now select the new extended cylinder and use the Context-menu > Intersect with Model, to cut the cylinder at the lower surface. Now select the unwanted faces/edges of the cylinder and erase them. You should now have a hole that pass right through the form ?

This section is very complex. Is there an object or picture you have sampled for drawing this section? Rather than correcting this model, it will be easier to redraw. However, it must be ensured that each piece is solid when redrawn. [image: TN56_1.JPG]

It's good practice to save & send .skp using some older version, even SU8. Online SU: Hnggggh. Cannot open.

I apologize, I didn't mean to hijack - accidentally posted in your thread. I was hoping the moderator could delete this post or start it as a new thread....

Thanks Box, you must be an owl. I awoke to find the printer guy fixed it with a program that "fixes" geometry.

Here you go. https://extensions.sketchup.com/en/content/sketchup-stl