Create an invert for a mould

[micheus]

That will be difficult in the current state...

- First of all, boolean will not work with co-planar faces (those faces overlapping the cube face, for instance), but this is a minor problem since we could to use Select->Similar Normals to select the STL_Object's top faces and extrude them allowing us to use boolean and then remove these extra faces;



- That STL_Object is in fact a set of 25 objects grouped. We need them Separated to be able to provide the fixes;

- By hidden the big objects we see there are garbage;


- From those garbage, the triangle is a face badly arranged (the green polygon) as well as the "edges" (which are in fact narrow faces - red lines);


Here is some steps that can be used to fix them

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This one requires more attention since there are two vertices overlapping each other and only one must be kept. Try to remove one and see what happen. Remove the one that requires less work from you to rebuild the faces or that creates less inconsistencies.
To see which of them you are about to select, check the information on top when you move the mouse closer them. You should see the vertex Id number. By moving the mouse around you may see the Id change.


These are some points to try guide you to fix the model before you be able to apply boolean operations as well other commands that may fail due too many mesh inconsistencies.

To fix an object with a bad mesh sometimes worst than model it entirely.
Is there a reason for you to be importing the STL file from another application instead of be creating the object with Wings3D and then export it as STL to be printed?