The red body was polished without primer, then sprayed in the following order: black → silver → red → clear coat.
The first black was sprayed three times until it was shiny. The silver was sprayed twice. The red was sprayed three times with Gaia Notes Premium Red, which has little hiding power. The clear coat was sprayed twice.
The black parts were sprayed with primer, then Prisb Blue Black, and then a matte clear top coat.
The gold plating remained the same color. The internal frame was sprayed with Mecha Primer Heavy. The white parts were changed to silver.

RG Sinanju candy paint | k-5's Gunpla works