The problem with gun control is that in the end, it turns out to be information control – and that isn’t easy. Japan has some downright strict controls on firearms – but this thing got next to the former prime minister:
No lathe. No Mill. A couple of pipes, home-made black powder, batteries to ignite the powder. Looks to me that the most high-tech component of the gun build was a large roll of electrician’s tape.
People have been making black powder for most of a millennium. Charcoal, saltpeter, and sulfur. Charcoal is easy to obtain. Saltpeter (potassium nitrate) might take a while – but you could use the Confederate Jno. Harrison’s method and get it from your own urine. Push come to shove, I could extract sulfur from sheetrock – from drywall. The Japanese assassin opted for electrical ignition – so I could do that with 9 volt transistor radio batteries.
The problem with keeping guns banned is that they are fairly simple tools – not so simple as an inclined plane or a lever, but still simple. A tube that is open at one end and closed at the end that includes an explosive or propellant charge. Basically a piece of pipe with an end cap.