Make Cordage from Blackberry Brambles

I’ve watched many videos on how to make cordage out of thistles, nettle, tree bark, etc. These plants provide great materials, but I haven’t found them in large quantities, or I’m afraid of damaging the environment during the collection process. So i decided to work with something that we have plenty of around here -- Himalayan Blackberries. Himalayan Blackberry vines are one of my favorite materials, because not only are they ubiquitous and renewable, they are an invasive species in Oregon, so the more