Solar Active Designs?

[csummerlin55]

I'm looking for something cool and different for our next trip. I was going to order some solar active thread (the kind that goes from white to a color once exposed to sunlight) to have the kids names embroidered on their towels but I don't know where to get the best deal on the best solar active thread. I was also wondering if anyone knows how to make a shirt that will change color in the sun without this embroidery thread.