For PPL & CPL I used to use - & teach -an A4 folder that was folded inside out so that the clip is on the outside.
Add a couple of A4 plastic envelopes held in with bulldog clips or similar & most charts, protractors, rulers, Wx & notams could be fitted. The whole thing was only about an inch thick.
Nowdays I use an A5 aluminium clipboard & nothing else. Charts & things I stuff down the side of the windscreen or keep in my headseat bag.