Guns are constructive and pro-peace. People who think otherwise may not have the perspective of ever living in fear or under oppression.
Human nature exists; there are people that for, whatever reason, have poor impulse control, no ethics -- whatever. There are humans who are prone to preying on those whom they feel are weaker.
In the past, the law of nature was simple: the stronger prevailed over the weaker. The youth prevailed over the old. The men subjugated the women.
Ruthlessness, strength, youth, aggressiveness... these things decided the outcome of most human interactions, for most of human history.
The gun changed that.
Put a handgun (or preferably, a carbine) into the hands of both of them, and a 90 year old grandmother can now have a meaningful conflict with an 18 year old 300lb musclehead. The conclusion is no longer foregone. And the musclehead knows it.
Arm the common goodfolks in society, and total violence decreases. Data supports this conclusion.
(to say nothing of the _moral_ imperative that honest people not be denied the use of arms)
The bottom line is this: arming good people reduces the aggregate amount of evil in the world. It turns the history of victimization on its head. The number of bad people who are "more effective" at being evil because of _their_ use of firearms doesn't compare to the amount of good that results from arming the good guys and thereby preventing more victimization, both in better outcomes when victimization is attempted, and from "herd immunity" because thugs are less inclined to attack people who will be harder marks.
Finally, the article summary is especially ignorant for implicating that Ghandi wouldn't 3d print guns.
"Among the many misdeeds of the British rule in India, history will look upon the Act depriving a whole nation of arms as the blackest. If we want the Arms Act to be repealed, if we want to learn the use of arms, here is a golden opportunity. If the middle classes render voluntary help to Government in the hour of its trial, distrust will disappear, and the ban on possessing arms will be withdrawn."
Mohandas K. Gandhi, Autobiography: The Story of My Experiments with Truth, Chapter XXVII, Recruiting Campaign, Page 403, Dover paperback edition, 1983. This book was originally published by Public Affairs Press in 1948.