There’s a technique called the Polaroid emulsion lift that allows you to transfer a Polaroid print to different materials, such as glass, rock, or watercolor paper. Essentially, you soak a completely dry photo (one that has set for at least 24 hours) in hot water and carefully peel the emulsion layer from the photo backing. The thin layer of film can then be carefully removed, spread over a new surface and allowed to dry.
The video above shows how the process works, and there’s a link to more specific details below. This is supposed to work best with type 669 film due to it’s really think emulsion layer. That said, people have had great results with other types of film, and a thinner emulsion layer will produce cool crinkly effects and tears, which can also be desirable.