Preheat oven to 450 degrees F (230 degrees C). Line a pizza pan with parchment paper.
Combine cassava flour, coconut flour, rice flour, baking powder, sugar, and salt in a large bowl. Whisk in eggs and olive oil. Add 1/2 cup water; mix until batter is the consistency of mashed potatoes, adding more water as needed.
Spread batter on the lined pizza pan with a spatula.
Bake in the preheated oven until dry, about 10 minutes.