My OCD is kicking in because the top corners do not match, where the side strips hit the beginning of the flap!😳🫣🥴…😂.. I will start my side strips at the top corners, so they can match going down, but maybe the envelope is not square?… Anyway I love the outcome, we used to do this all the time as kids.. we cut shiny colorful magazine pages, into strips then folded them longways Also book pages and even ribbon we could also fold in half long long ways.. I’m 70, and we called it “Iris Folding”🎉❤(also sometimes we took thinner blank paper and painted with thinned out paint… you can cut a shape out of a card top, that you have cut and then make a piece of the folded strips, bigger than then empty shape, then glue or tape it behind the hole!.. flue the whole top on the front of your card blank!… Or just frame the front by it self for a pretty picture to hang up!( the shape of a Moose head with the iris folding behind it that had, small patterns of trees or leaves, elk or wolves,in Mountain type colors of the forest was the last thing I did for a Christmas present!… My friend returned the surprise for my birthday only she did black paper behind her cutout that was done with folded strip s on the surrounding paper… that was super beautiful!… But…what fun for any age!🎉❤