In a large bowl, whip heavy cream until stiff peaks are achieved, about 3 minutes.
In a separate bowl, combine sweetened condensed milk and vanilla extract. Fold whipped cream into milk mixture until combined. Divide mixture evenly between two bowls. Add orange extract to one bowl and lemon extract to the other, folding to combine each. Then, divide the orange mixture into two bowls, and the lemon mixture into two bowls, making four bowls total.
Add food coloring to each bowl - pink, purple, blue, and yellow (or your desired colors). Gently fold to combine.
In a loaf pan, add dollops of each color to fill the pan. Once the pan is halfway full, add half of your rainbow sprinkles in a single layer. Once full, add remaining sprinkles on top. Run a butter knife through the ice cream a few times in each direction to make a swirl pattern.
Cover and freeze for 4-6 hours, or overnight, until firm.
Extracts can be substituted with your favorite food extract flavors. Or, omit lemon and orange extracts to make vanilla ice cream.
Homemade ice cream will keep for up to 2 months in the freezer in a tightly sealed container.
I used Betty Crocker Gel food coloring in yellow, blue, neon pink, and neon purple. Any food coloring (including natural coloring) will work in this recipe.