Summary

Calcium, carbon and oxygen atoms for construction of Calcite ball-and-stick model.
Model sizes (diameters):
Calcium - 22.7mm; Carbon - 14.7 mm; Oxygen - 13.4 mm;
Holes - 2.1 mm.

Example of final constructed model see on: https://skfb.ly/oUFKG
In this example, there are 33 calcium atoms, 26 carbon atoms, and 78 oxygen atoms.
There are 78 C-O bonds, 96 Ca-O bonds, 24 Ca-Ca bonds, and 24 C-Ca bonds.
The bond lengths: C-O - 28 mm; Ca-O - 51 mm; Ca-Ca - 109 mm; C-Ca - 93 mm.