MaintainVolume constraint squashes/stretches object along given axis.
Check the preview image below:
Here we explain each options in the MaintainVolume editor;
Volume section contains three parts: Base, Axis, Multiplier.
Base value is calculated with scale.x * scale.y * scale.z and is automatically set when MaintainVolume is added. Usually you could modify the Multiplier field instead of directly manipulating this.
Axis specify the axis that will trigger the squash/stretch, only scaling on that axis will make the GameObject squash/stretch;
Multiplier is a parameter used to multiplied on Base;
The result scale would be: < Sqrt(Base*Multiplier/y), y, Sqrt(Base*Multiplier/y) > when Axis=Y;