You need to post a finished one when you figure this out. Very interesting.
Would clear contact paper work?It's cheap and you can buy it by the roll.
Buy printable sheets of treated fabric that can be found at most craft/sewing type stores and then use a plastic (I have some from Walmart like what can be used to cover furniture or table tops) to stitch on top of the photo. You can even drop in some FSL snowflakes if you want.
I believe what you are looking for is called "transparency film." It can be a bit pricey and be sure to get the type appropriate for inkjet--the type for laser printers tolerate the heat necessary for laser printing but is unlikely to absorb the ink of an inkjet printer. Check your local office supply store--or if you are lucky, a second-hand store or university surplus sale.
I have seen these done with actual photos cut out and then laminated. Not sure if it is similar to what you are wanting to do but it sounds intersting. Just search up photo snowglobe ornament and a few tutorials come up