1. Create a rainbow swirl on a very small piece of fabric, roughly 6" x 6".
2. Leave a part of the fabric undyed for the white lettering.
Hi, Jon. For the rainbow swirl, I would use the same method as with any swirl: I use a small fork to twist the fabric into the swirl, then I would use small rubber bands to hold the shape. This works on infant shirts, so it should work okay on a 6" by 6" cloth.
For the lettering, I would suggest 2 methods: the easiest would be to dye the fabric, then use diswashing gel with bleach and a stencil of the letters - place the stencil where you want the words to appear, then use a foam brush to carefully dab the gel over the letters. Let the gel dry completely, then wash out. I have had good luck with dyes bleaching out to white this way. A more involved method would be to use soy wax to cover over the letters before dyeing - the soy wax will melt if you use hot water to wash the piece after you have batched it.
Good luck, and let us see the results!
Judy