You can add variety to your blocks by making them dynamic. The two most useful applications for dynamic blocks are multiple presentations of similar objects and manipulation of components within individual block inserts.
AutoCAD's dynamic blocks feature gives a great deal of flexibility to block creation and insertion. But it's also a very complicated system, with its own set of commands and system variables. I recommend that you become very familiar with regular block creation and insertion techniques for creating and inserting blocks (which I describe in Chapter 17) before you tackle dynamic blocks.
Spend some time planning your dynamic blocks. Sketch out the geometry for each variation in appearance (or visibility state) and decide where the common base point should be. Unless you're a lot smarter than I am, you'll probably find that creating dynamic blocks is complex enough without trying to design your blocks as you go.
If your drawing shows six different kinds of windows, one approach is to create six different standard blocks to represent them all. Alternatively, you can create a single dynamic block and define visibility states to cover all six ...