To create a custom property:
- Select the object to which you want to assign the new property.
- In the Properties window, click Editor.
- In the Property Editor that appears, select the Custom Properties pane.
- Drag a property type from the Add Property area onto an object in the Destination area.
Tip: You can also use the Add button to assign selected property types.
The custom property is assigned to the selected object.
- To rename the custom property, select the custom property in the Destination area, double-click in the Name field, type a name and press Enter.
- When you close the window, the new property displays in the Properties window.
- In the Properties window, click the custom property’s Animate (A) button so that you can use it in constraints.
- Connect the custom property to objects.
See Animating Using Constraints, Mapping pose and keying group properties, and Creating a custom keying group.