Step 1
Creation of the block shell using the Construction > Block Envelope > Block Envelope... or Construction > Block Envelope > Constrained Block Envelope...
Step 2
Creation of the component using the block envelope's edges and faces
Step 3
Creation of the component family document
Drag and drop the block shell from the Geometric Generics folder into the Drivers folder
Step 4
Inclusion of the Family document into an Assembly document
Selection of a target block or housing
or creation of an block envelope with the 
button.
The component
is automatically redimensionned according to the target block