Funny idea!
It's probably feasible but not so easily: straight and curved tracks can be designed with their borders thanks to rooms and walls. More complicated stuff like bumps and hollows could be designed with curved walls exported to OBJ format then reimported and rotated 90° during importation.
On the other hand, I don't see how you could design banked turns with Sweet Home 3D, but as far as I can remember, this kind of track is generally not found in a miniature Golf.
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Emmanuel Puybaret, Sweet Home 3D creator
