For my third pour, I decided to give overmolding another try. This time, I knew to watch out for the plastic absorbing through the seams. I got some acrylic sealer from my TA and planned to use that. However, I didn't want to risk the plastic not sticking to the ball at all, so I only wanted to spray the seams with the sealer. I covered the ball with painters tape, and cut away the parts covering the seams. This way, only the seams would be exposed to the spray.