To smoothly assemble, it helps to pre-fold the creases.
1. Insert part ①
2. Shape and fold up to the center position.
3. Close part ②
4. before closing part ③.
5. Insert while covering the outside.
6. To facilitate easy opening, close the lid with a semicircular opening first.
7. Finally, close the outer lid to complete the assembly.
Since it can be reopened, it's safer to insert the bottle last.