Make Guides from Objects

Not satisfied with only horizontal or vertical guides (and why should you be)? Then make your own. Create any object you want to use as a guide, make sure it is selected, and then from the View menu choose Guides>Make Guides (or press Command-5 [PC: Control-5]). To turn your guide back to a regular object, first unlock the guide using Command-Option-; (PC: Control-Alt-;), then use View>Guides>Release Guides (Command-Option-5 [PC: Control-Option-5]).