The sides and lid dressing are glued with double-sided adhesive.
To glue the dividers, the double-sided adhesive proved inadequate on such a small surface: after a moment, it peels off. So I tried a new solvent-free glue (important for polystyrene and for plastic models health): Pattex 100%. Without having much hindsight at the moment, the gluing seems satisfactory. But since the hardening is not instantaneous — count several hours, I had to provide a system to keep the dividers standing during drying: spacing wedges having the exact width of the future cells.
These wedges are made of a sandwich of different materials of well-defined thickness to obtain a regular spacing.
Naturally, if you are more gifted or better equipped than me to get well-levelled and parallel faces, you can make these wedges one-piece blocks, for example wooden.
They are beveled about 3 mm at the bottom to avoid being glued at the same time as the dividers if the glue overflows a little. Tip: mark the upper side of the wedge.
To get fairly straight dividers, at least three rows of wedges should be provided: one at each end and one at the center.
I proceed as follows:
When the last series of wedges is placed, blocking the assembly, I place a block of expanded foam over the dividers (to compensate for the divider height unevenness), then a hardboard sheet of dimensions somewhat smaller than the box interior, and finally a 5 to 10 kg weight (a can of ironing water, well closed!) to hold well the whole. I let it dry overnight.