Barpapapa cake

The tye-dye technique:

I divided a large batch fondant into 6 sections. I dyed each section a rainbow colour and then rolled each section into tubes and then coiled the tubes into a giant circle. I placed the circle on baking paper and then used my kitchen roll and rolled the whole thing to the disired thickness.

I didn't have to brush the seams with water, but if your tubes won't stick; just apply a tiny bit of water in the seams and let it sit and rest for a couple of min.