Let's take a look at another idea you can use for your handmade change of address card. (Or any card, for that matter!) The design for this card was a result of the 'ole "necessity is the mother of invention" crisis. I only had one red panel left and I didn't want to waste an entire sheet of cardstock to make another one, so I grabbed a scrap of satin ribbon and came up with this:
The bottom flips down and then the top flips up to open the card.