1. No they wont, plastic guns still wont be the same quality as professionally made metal ones.
2. Same can be said about other types of weapons. Stab someone and throw it in a river, odds are finding it are pretty damn low
3. Like that stops people now, tell that to criminals that dont have to be citizens now and still get them illegally.
4. TSA cant even stop metal guns and other weapons passing through metal detectors
5. Being light in weight doesn't equate to being more likely found if it's packed properly on a person
6. One that would imply that kids have easier access to these devices, sorry but these aren't made, yet, from makerbot type devices. They still require the more industrial style machines to make it, as well as access to bullets to fire it. Children have easier access to knives then they do to machines that can make a gun that would be strong enough to even work let alone the materials and bullets needed. Any kid with enough intent to actually pull that off wont let the lack of a 3D machine get in the way of them doing harm.
Your post is nothing more then FUD.
2,3,4,5 aren't valid counterarguments to gun control and I find it hard to believe you all keep spouting those off like that means we shouldn't regulate guns to make the country safer. Your post is nothing more than fud.