Watertight Stackable Soda Bottle Cap Box 2.0

I liked the original idea quite a lot, but I felt that the original containers needed some rework.
These have a square footprint (easy line-up, easy stacking), and they come in two flavours:

One has a cubic volume, the other one a spheric.

Both have "open" and "closed" variants: the "opened" variants provide a view into the inside, the "closed" variants are easier and faster to print and can contain liquids (ink, shots, etc.).

They contain approc. 20ml in the spheric form, 25ml in the cubic flavour.

They can even be printed transparently, using glow-in-the-dark filament or in a silky metal look.