A 35mm slide printer?? I guess its an easy way to make prints from slides but would it serve any purpose to transfer a transparency to a polaroid neg?? I guess it would be a larger neg that you could print from. Just curious. Sounds fun, even if pointless.....
These are mainly used for printing slides and emulsion transfers and lifts.
You could go from a color or B&W slide to 665, I suppose, and contact print using an alternative process or you could use it as an interneg for enlargement on conventional paper.
IMO, the main advantage of using 665 in a Polaroid slide printer is you get not only an internegative, but also panchromatic conversion of color to B&W. Of course, you could also save money by loading conventional 3x4 film sheets into empty Polaroid packs (in a darkroom, of course), then developing them as you normally would sheet film; this would give you costs of 30-50 cents per negative instead of something like a buck and a half...