you can easily reuse old or failed Polaroids by opening the back and inserting a new photo.
also on my blog
Step 1: Suplies
you will need
optional: You can edit your photo on such a way it actually looks like a Polaroid, PicMonkey has a Polaroid effect option.
Step 2: Open
open the back of the Polaroid by picking the upper edge loose.
Step 3: Cut
Cut your picture in a square so it fits in your Polaroid.
Step 4: Insert and Paste
insert your photo and close the edge again with some glue.
tadaa your done!