Bombs are quite easy to build now that we have the internet. People who want to kill people will find a way to make maximal casualty...by buying weapons legally or illegally.
The real issue is cultural, Switzerland is armed to the teeth and every citizen has a gun, yet no mass-shooting issue. There is a big discussion to be had about mental illness, the education system, fatherless homes, etc. But all we talk about is the weapon these sickos use kill people.
RE: Reality Check: Trump Did Not Make It Easier for Severely Mentally Ill People To Buy Guns