In my job I print a lot of various sized envelopes for event invitation mailings. There are always practice pieces and misprints: I used to just toss them, but it finally occurred to me that I could recycle them into mail art.
Here are a couple of works in progress, painted and stenciled with a make-up sponge. they still need some embellishment--stamping, washi tape, transfers, stickers, etc. and then they will go out stuffed with artsy goodies.