>> Not sure that it developps object as volume result ? Only as surface ...

Frenchy: Yes, the result is a surface, but this surface is calculated depending on the material and the material thickness to unroll. Let me cite the manual:

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Material: Use the "Material" menu to select the material (e.g. paper, steel, PETG) and material thickness to use. Lamina will take your material and its thickness into account when designing the 2-D cut path, to assure a proper fit of all the final pieces
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