Problème Booléen

I am a sculptor and jeweler in real materials if you allow me that expression, and currently I am learning to work with 3D logialls. A little Blender but especially Nomad Sculpts which I love. But I’m learning on my own but now I need help. I can’t “cast” my objects into Booleans. Is this necessary to produce a StL file? There’s a strange phenomenon happening, when I try to blend certain details together, sometimes it erases others. However, I know the principle, that all the selected objects are visible and not grayed out by the grid. So, two questions: To go to the 3D printer, are “linked” objects enough to produce an STL file, Why do objects sometimes erase others by fading Booleans? Thank you for your help