Based on this XPS model: https://www.deviantart.com/rotten-eyed/art/ascendant-one-hestia-795532756

I'm having trouble with 3D Builder again, so I ended up repairing this model in Meshmixer with the "Make Solid" tool instead. This makes the model printable but kills a bit of the surface detail. I decided the result was good enough for the scale I was printing at.

The STL model is the repaired one that should be used for printing, the OBJ + MTL version includes textures.