Hair comb, friendship bracelet thread and scissors. Easy!
Start with your first color and tie a knot to get started. Start wrapping the string under and then over as many times as you need to make it as thick as you want.
When you finish with one color, tie a knot with the next color and begin wrapping the next color.
On the color before the last one (in my case, the last yellow) leave a little extra string so you can make a knot with that one and the last color (dark green) because the last color will not have a next color to tie on to.
Once you tie the last color to the color before, you're done! Enjoy!