How to work with *.stl mesh, how to Transfer in solid Bodys?

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1

I have some mesh files - and I’m not able to work with this for me important files. I want to,cut or change this mesh bodies. Please help me to transfer this mesh figures in solid bodies. How is this to,do?
Imsee that some others have the same problem. Can You include a tool or apli action, that makes this possible?

2

There is 2 methods described in this post.Is there any way to work with an imported stl precisely?

Freecad and Fusion can convert STL but you will need to do some cleaning up.