A good way to make your own personal seals is with Crayola Model Magic. Simply, roll out a small ball of the clay. Then, imprint this ball with a small rubber stamp or a brass seal. In this way, you can create whatever stamp impressions you can imagine.
If you have some metallic dusting powder or gold acrylic paint you can get a super effect using a dark red ball of clay (most wax seals were made with red clay) and then dusting the corners, when dry, with gold or silver.