This might be one of the coolest 3D jobs I’ve seen in a long time! Not that it’s all too complex but it really emphasizes how useful a 3D printer can be for consumers. Nice work!
And yes, scan/mirror in slicer. But, my preference would be to scan as STL into CAD then refine it from there. It has been a long time since I’ve scanned anything, but my recollection is that 3D Scanning can be less than useful on its own.
You could also 2D scan (aka take a picture :)) then create 2D views that you would stitch together.
If you do 3D scan into your slicer and mirror it, I’d really like to know how that works out for you.