I like to call it re-purpose because it really is going to a new fun purpose. Recycle sometimes has a negative connotation to me..like stinky garbage. Well, this is no stinky garbage. It is cuteness, and any old envelope will work. I use greeting card envelopes because they are usually colorful. But I use just ordinary envelopes, those that come enclosed with bills for easy return are fun because they have nice lines to write a message (Mom, don't fret I pay my bills, I just do it on-line) canceled stamps add a fun flair. Cut the corner of the envelope into a heart shape. I made a template so I can do it quickly. Tiny envelopes all ready for secret love note giving...or to containing tiny treasures. Also make great book marks slipped over the corner of the page. Now start opening those letters at the bottom and keep those fun canceled stamp corners for a new purpose.