Put some paper towels in the radio compartment and motor area.

Inspect the surface of the model one more time. If there are areas that need to be fixed then address them now. I used a lightweight polyester body filler. Mix and apply. These dry in a few minutes. Sand as needed.

Once the surface is smooth it is further filled with a mixture of Spackle and water. About 2 teaspoons were mixed with a little water.

This is spread over the entire finish. Just work the mixture into the surface with your hands (gloves are recommended).

Let this dry overnight.