Summarize the following:
Look for Styrofoam balls that are around 1 inch (2.5cm) in diameter. Make sure you get white balls since you'll need to paint them different colors for your project. You can find Styrofoam balls at your local craft store or online. Use red, blue, yellow, and orange to paint the balls in the piles. These balls will make up the inner strands of your DNA model, which represent guanine, cytosine, thymine, and adenine. When you're finished painting each ball, set it aside to dry on a sheet of newspaper or a paper towel. You should have 6 red balls, 6 blue balls, 6 yellow balls, and 6 orange balls.

Summary:
Purchase 48 white Styrofoam balls for your project. Split the other 24 balls into piles of 6 and paint each pile a different color.