Where were 2nd amendment people when bomb materials were banned or regulated over time? Where were they when rocket launchers and mortars and grenades and land mines were made illegal? Where were they when full auto weapons were regulated? And why aren't they marching in the streets to change these laws?
It seems to me that people who say they're for the 2nd amendment really only seem to get in a twist about currently legal, currently for sale weapons, the way one might if, say, one belonged to an industry lobbying organization that made money based on sales.
Yes, you can improvise a weapon out of an ash tray. But they seldom outfit armies with baldoliers of ashtrays, do they? A huge part of the success of getting knives legalized has been educating the public about knives as a tool that can be improvised into a weapon, not as primarily a weapon. Educating people that many illegal features are cosmetic, or for user safety. I like to say, knives are used to feed, to create, to reveal, and to heal. Guns can't fire themselves, but they can't be used for any purpose but killing or mock-killing. You can gather food, if that food needs killing. You can have fun, practicing killing. Or you can kill with them. Those are the options of a weapon, not a tool.