The left is good but the right side is messed up. How to make everything flat without extensions thank you.
Without extensions: create a plane bigger than the model you have make it a group and place it under the geometry with a separation, then extrude all the faces you have so it intersects with the plane, get inside the plane group, right click on it go to intersect with model and you’ll have everything flat.
If you want you can share the model and I can flatten it for you using vertex tools, it takes literally 3 second to do that.
Thank you for the file and for the method.
It takes more than flattening to create those faces. Either you draw it correctly in the CAD program, or you solve each of those points (delete edges or intersect some) in SketchUp.
One way to flatten is to go to top view, parallel projection and export a 2D DWG file to full scale, and bring that back into SketchUp.
What version of SketchUp are you really using? Your profile says SketchUp for Schools 2017 but there is no such version. SketchUp for Schools is web based and doesn’t allow the use of extensions. Please correct your profile.