When people talk about electronics and environmentalism, they tend to talk about planned obsolecence, rare earth metals, or pollution from manufacturing or recycling, which are all big problems of course, this is also something I’ve been wondering:

Most higher end electronics have metal casings made by CNC milling a solid piece of aluminum, magnesium alloy, or another metal. I think it was first made popular by Apple with their Macbooks. The first problem that I can think of is that a casing needs to be hollow, so you’re starting out with a solid piece of metal and carving it until most of it is gone, and even though the metal shavings can be recycled, both the CNC and the recycling process require energy, and the milling process also requires a constant stream of petroleum-based lubricant (though I’m not sure if you can just use something cleaner like water or if the oil can be reused).

Even if one uses electronics for as long as possible before upgrading (in which case most people want to future-proof by getting something higher end), do metal casings pose a sustainability problem? How does it compare to its main competitor, making casings out of plastic? Are there any other alternatives that are better than either? Maybe cast metal casings?