A ball of energy charged by the light of the sun.
This tech needs to be done with access to sunshine, preferably outdoors though you can make a small, weak one for practice using the sunlight that comes through a window. Cup your hands to make a Ki Ball, and instead focus on the way the sunlight feels passing between your hands. Using willpower, keep the sunlight from leaving your hands while allowing more in, creating a ball of sunlight energy. This ball can be used for attack, though you should add some of your Ki to the ball so you can control it better.