How to make swirled colors in fondant.
1. Choose two (or more!) colors, in proportions that you want for your finished product. (For instance, if you want a mostly red finished fondant shape, use more red than any other colors.)
2. Gently knead the colors together, just until they're gently combined but each color is still distinct.
3. Use a plastic rolling pin to roll out the swirled fondant in an even layer.
4. Use fondant cutters to cut out desired shapes. To reroll and use the fondant, stack the scraps on top of each other and gently knead just until combined, then roll out. Avoid overkneading the fondant, or the swirls may blend together.