Summary

Calcium, carbon and oxygen atoms for construction of aragonite 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/p9OWq
In this example, there are 9 calcium atoms, 14 carbon atoms, and 42 oxygen atoms.
There are 42 C-O bonds and 54 Ca-O bonds.
The bond lengths:
C-O - 28 mm;
Ca-O - 55 mm (24 bonds), 58 mm (12 bonds), 53 (12 bonds), 52 (6 bonds).