This is a keyring in the shape of an atom, specifically referring to Ernest Rutherford's atomic model. It can also be used as a medal, as if it were a kind of award.

I designed it for my students. The letter Z is in the nucleus of the atom, referring to the atomic number of the elements.

It only requires a colour change, so it is easy to make even if you do not have a multicolour system. In fact, I do not have that system; I printed it with the Elegoo Centauri Carbon.

I used 20% infill and PLA as the material, but you can use whatever infill you want. As it is small, the difference in the amount of material is not that significant.