Gather your supplies. I printed an 8x10 sheet of Instagrams at Costco for $1.49, and the magnets cost me $5. The 2"x2" tiles were $2.50. Mod Podge, glue gun and paintbrush I had on-hand already.
Cut your Instagrams into individual images. (These make cute photo-booth-like strips, too!)
Apply enough Mod Podge to adhere an image to the surface of the tile. It dries clear, so don't worry about being a little messy.
Place your image on the Mod Podged tile, and paint it with another layer of Mod Podge. Make sure you cover where the edge of the image meets the tile.
Repeat for all of the tiles. As long as you move somewhat quickly, you'll have enough time to Mod Podge all of the tiles first, and then lay the pictures down. Once they're all coated, let them dry.
Once your tiles are completely dry (roughly 30 minutes depending on how much Mod Podge you used), use your hot glue gun to adhere a magnet to the back of each tile. Let them dry (less than 10 min).
Put 'em on your 'fridge and admire your work!