Wired's Ghost Gun

I Made an Untraceable AR-15 ‘Ghost Gun’ in My Office—And It Was Easy:

"I looked down at the fully built rifle and something in my brain shifted. I realized that the abstracted parts I’d been fiddling with had turned into an object capable of killing someone. My lower receiver had transformed from a “gun” in a legal sense to a “gun” in a very practical sense."

Abstracted parts... an object capable of killing someone... that could be said of many things. I'm not sure why guns seem to have some magical power that makes them so different from other tools - from hammers to cars - that can be used to hurt or kill someone.