There is a great horizontal
double pocket card in MaggieMay's gallery. It's made with a single sheet of cardstock, but only makes a card that's standard size, not the 6x6 that you want. (But you need to consider the postage change with square cards!) The folds on her card are easy, once you get the hang of it, and you can fold the "non-pocket" piece either in front or in back of the pockets, depending on your preference. Good luck with your search--no pressure, Mom!