I've been thinking about the materials the manufacturers use when making empty cartridges. As long as I know, the metal cartridges are made by copper with nickel plated, which is not good for our health. If you want to get a healthier alternative, you have to go with the full ceramic cartridges (including mouthpiece). But the full ceramic cartridges are much more expensive and they sometimes crack themselves. I am thinking why no one wants to make stainless steel cartridges? Since it's healthier, wouldn't cost much more than using copper and at the same time stable. What do you guys think?