Backpack shown utilizes the previous concept, expanding zippered bag/ pack entrance – color marking sheme is similiar to linked post.
Flap opened, entrance still closed, and zipped:
Entrance opened, un-zipped:
After that, blue and purple marked pieces are turned out, and access is granted. A piece of drawstring prevents them from doing this. I didn’t shoot it because can’t decide how to do it apparently and evidently. And another reason, my camera makes very poor shots in dark conditions. Well, maybe i’ll try later.