The easiest way to create your own master slide is to find one that's similar to what you'd like to create, and use it as a starting point. You may not be interested in changing all of the master slide attributes listed above, so if you can find a master slide that's partially configured the way you want it, you can save yourself a lot of design time. Of course, if you really do want to do everything from scratch, start with a blank master slide.
Begin your master slide modification process by duplicating the master slide you're starting with so you can either keep the original in your theme, or come back to it to start over again if your first modifications don't pan out.
Select the master slide in the master slide organizer, and then click the toolbar's New button, or press Return. Alternatively, you can choose Edit Duplicate, or choose Slide New Master Slide. No matter which way you do it, Keynote makes a carbon copy of the master slide and displays its thumbnail in the master slide organizer. Double-click the new master slides namewhich is something like Master #12 and give it a descriptive name . Begin work on the new master slide by opening the Master Slide Inspector, which takes the Slide Inspector's place when you have a master slide selected (Figure 12-2).