Using the excellent open source software that's available it's pretty easy to make a printable model of a circuit board, here's how I usually do it:
Once I have a board designed in KiCad I export the .vrml file:
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Then I import the .vrml file into MeshLab:
MeshLab
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And export it as an stl file:
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Now the Stl file can be imported into OpenScad and can be used to design a case or whatever else you might need to do with it:
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