Typically, when I make an over sized card it is going to be hand delivered so the packaging doesn't need to meet postal guidelines. I call the envelope I use the most a slide pouch. It is quick and easy to make.
I take 6x12 piece of cardstock and score it at 3.5 and 8.5. After it's scored I cut a half circle somewhere between the two score line. Next I score tape one end closed and then fold the scored lines and adhere them in the back. I like to wrap a different color band around the middle and decorate it to coordinate with the card.
For the card, I used my daughter's idea of punching out the butterfly trail and backing it with a different color to coordinate with the washi tape.
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