Value range: 0/1
Value = 0:
Do nothing
Value = 1:
If an assembly mass is given use it else calculate assembly mass from sub parts.
Calculate total assembly volume from subparts.
Get all non empty subparts.
For each non empty subpart:
Calculate subpart partial mass = ((subpart volume / volume of all subparts) * assembly mass)
Calculate subpart density = subpart partial mass / subpart volume
Assign calculated subpart density (instance only)
