Right now I am using a Mead Five Star “Flex Hybrid Notebook Binder”. I think it fits all of your criteria: -It uses replaceable sheets of paper like a looseleaf binder. -It would only be as thick as the thin (but sturdy) plastic front and back cover and the amount of paper you put between. -It completely folds back on itself -It uses 8 1/2 x 11 3 ring binder looseleaf paper, so lots of tasks can be visible at once. -The rings do not take up a lot of space. This is a link: https://www.staples.com/mead-five-s...-sheets-assorted-designs-08120/product_865918 Or this: https://www.amazon.com/Hybrid-NoteBinder-Binder-Notebook-72011/dp/B003O3H2G0 I will admit that one drawback/con is that the rings are not effortless to open. You have to physically pull apart each of the 3 rings in order to open them to add or remove paper. But it meets all your other criteria. I use it with Post It flags or tabs for dividers, such as these: https://www.staples.com/Post-it-Stickies-Flags-Tabs/cat_CL165756 BTW I do not profit when you click on those links. It is on my someday/maybe list to learn how to set up affiliate links, so that when people click on my links, I profit if they purchase. But it is not an active project yet. Hope this helps.