Cacti have different kinds of spines and spikes depending on their main purpose. Some are defence against predators – it difficult to munch into something with long thick spines all over it. Some are for collecting moisture and providing shade so are finer and more delicate, and some are for insulation against cold and heat. These are intrinsic to the shape and structure of cacti so I had to get them right. I solved this with a combination of very thin stiffened silk nuno felt cut into thin strips and tiny glass beads.