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How do you handle printing supports for the main part? Sorry I'm new to 3D printing.

I'm using slic3r PRUSA edition on my PRUSA Mk3.

I assume the object should be rotated 90deg on X axis prior to print so that its printed on its side too?

Also seeing something strange when I preview the object in slic3r. It seems to have excluded a section of layers towards the top of the object...