> They're much less concerning to me because their rate of fire is extremely slow.
Not if you make a multi-barreled one and spend some time practicing. [0] Go check out some youtube videos... some of those kids are kinda nuts. But, okay, I believe you when you say that you're unconcerned about firearms with a low rate of fire.
> I don't know the details of what can be printed in a consumer-grade printer...
I expected this, yeah.
With a consumer-grade 3D printer you can't print the things you need for anything much better in the rate-of-fire department than a "slam fire" firearm. To make a semi-auto firearm, you need springs and a rod that are fairly strong and heat resistant to make the shock absorber that drives the gas-powered mechanism that ejects the empty cartridge after firing. You also need a cylinder that can contain the pressure and heat of the gases from the burning powder in the cartridge, as well as provide a straight guide for the bullet so that you hit what you're aiming at. For reliability, you'll probably want a metal firing pin. Your rate-of-fire concerns mean that you're worried about magazine-fed firearms, so you also want decent springs in the magazine to reliably feed ammunition.
Because you're concerned about firearms that aren't low rate of fire, all of these things need to reliably perform for more than a handful of firings.
> ...but I've seen things claiming to be pretty complete kits...
Looks like you never did the inventory on those kits. For any kit that is actually going to give you what you're scared of, you'll find that the parts of the firearm that actually do the hard work are not going to be 3D printed.
You've professed ignorance of what can be printed in a low-end 3D printer, but do you happen to be familiar with what can be made in a high-end 3D printer? If you are, would you care to tell me how much money you need to pay for a 3D printer that will generate reliable springs, shock-absorption assembly, and barrel that will function for more than a couple of shots?
> If it's not actually possible to 3D print an effective gun, perhaps someone should make that argument in detail.
So, there's the video at [1]. That's the guy's second attempt at a barrel for .22 caliber ammo, and it's... ineffective. I also want to call your attention to this short Popular Science news article from fourteen years ago. [2] Notice the discrepancy between what's described by the headline and the article body "3D printed assault rifle made from ABS!" and the truth exposed by the picture of the actual firearm... the important parts of the firearm are made of metal, rather than ABS.
I mention that Popsci article to demonstrate to you that the "3D printed gun" hysteria is not new, and the folks making the claims that one can just go up and get a fully-functional magazine-fed semiautomatic pistol or rifle straight (and entirely) from one's consumer-grade home printer are just lying.
[0] Anyone who has decided to use "slam fire" firearms to harm someone is clearly unconcerned with safety, so they could even make several to dangle from their belt to increase their effective rate of fire.
[1] https://www.youtube.com/watch?v=5AA0R11oU90>
[2] https://www.popsci.com/technology/article/2012-07/working-as...>