If you are rolling say three pieces of nettle, lay them down on you thigh and make sure they are different lengths then role them on you leg in to a thread, as you work your way towards the first loose end add another piece of nettle. Then as you come to the next piece do the same again untill you have a good length then take the hole length, about 3/8 along the length make the thread kink up, by twisting the thread tight. Now all you have to do is carry on twisting until you get to the first end all should be clear by then.
Sorry if this makes no sense its the best i can do.