What is a good circular loop of metal for a science project atom?

Reporting back, and thanks for your help.

Here's her project, where a single tomato wire cage was turned into the standing and hanging (either way) model of the silicon atom.

Protons are the walnuts. Neutrons are the chestnuts. And pumpkin seeds (much smaller than acorns) are electrons.

The first energy level (1s2 orbital) is further from the second energy level (2s2,2p6 orbitals) which itself is closest to the third energy level (3s2,3p4 orbitals).

The other kids' projects are shown here, where most didn't even try to create round loops which are 3D in shape.