Each box requires 8 square sheets (4 for the lid, 4 for the bottom).
You can see I really like folding the model, I made so much of them (and more, that I gave away before taking the pictures). The three boxes above are made from: leftmost, 7.5 cm kraft paper; top, Showa Grim washi chiyogami 15 cm; right, japanese chiyogami and Tant 15cm.
Papers: left, Aitoh RobinJoyRiggsbee pencil drawings + white Tant for the interior ; middle, Vivi Gade “Paris” paper ; right, Dovecraft “Back to Basics” Monochrome (150 gsm), all in 15 cm.
Papers: middle, japanese chiyogami 7.5 cm ; left and right, 15 cm japanese paper (all is in japanese on the box, can’t give details).