Wow - what a great DIY for displaying photos! If you're using tiles, you could probably buy those wooden or plastic frame display holders (the ones that fold in half that you use to display plaques and such). If you're wanting to
display them on the wall, I'm sure you can get hooks from the hardware store to glue onto the back with a strong adhesive. Of course, these are all just suggestions - I've never actually tried this, but it looks like an awesome idea!!
You could also try and refurbish old picture frames you have lying around...flea markets are great for that as well! :) HTH.