3D printed gun designs these days don’t even use plastic for most of the critical parts. The goal is to print a frame, which you can then assemble into a full gun using durable off-the-shelf parts that are available from any hardware store. No need to 3D print a bolt (and deal with all of the manufacturing issues that entails) when you can just buy a bolt for 5¢ at any hardware store. Especially when that bolt will be more precise and durable than the plastic bolt you would have printed.
It’s the old carpentry idea that if you can’t get precision by hand, you can borrow it from something else. Need to cut a bunch of identical boards, with precision in 64ths of an inch? A #8-32 bolt will have 32 threads per inch. So a half turn on the bolt will advance or retract the bolt 1/64 inches, accurate down to whatever the bolt manufacturer’s clearance is. Probably a few thousands of an inch. Build a jig to hold your boards at the saw, and thread a bolt into the jig to act as the board stop. Now you can turn the bolt to adjust your clearance as needed, and you’ll be accurate down to 1/64 by only making half turns each time.
And 3D printed guns use the same concept. You don’t print a plastic barrel that will explode after two or three shots, you just leave a void for a store-bought pipe to fit into the frame. The pipe will be more durable and more precise than anything you could feasibly print. You don’t need to 3D print a firing pin that will blunt/shatter/jam after a few uses, when you can just use a steel nail that will have better durability and avoid jamming. And all of the parts you need can be bought at a hardware store without raising any suspicions. That’s part of what makes this so dumb. They’re not just requiring printers to scan for potential gun parts. They would require printers to scan for anything that could potentially hold or manipulate gun parts. And that is a much broader spectrum than simply scanning for the shapes of the parts directly.
3D printed gun designs these days don’t even use plastic for most of the critical parts. The goal is to print a frame, which you can then assemble into a full gun using durable off-the-shelf parts that are available from any hardware store. No need to 3D print a bolt (and deal with all of the manufacturing issues that entails) when you can just buy a bolt for 5¢ at any hardware store. Especially when that bolt will be more precise and durable than the plastic bolt you would have printed.
It’s the old carpentry idea that if you can’t get precision by hand, you can borrow it from something else. Need to cut a bunch of identical boards, with precision in 64ths of an inch? A #8-32 bolt will have 32 threads per inch. So a half turn on the bolt will advance or retract the bolt 1/64 inches, accurate down to whatever the bolt manufacturer’s clearance is. Probably a few thousands of an inch. Build a jig to hold your boards at the saw, and thread a bolt into the jig to act as the board stop. Now you can turn the bolt to adjust your clearance as needed, and you’ll be accurate down to 1/64 by only making half turns each time.
And 3D printed guns use the same concept. You don’t print a plastic barrel that will explode after two or three shots, you just leave a void for a store-bought pipe to fit into the frame. The pipe will be more durable and more precise than anything you could feasibly print. You don’t need to 3D print a firing pin that will blunt/shatter/jam after a few uses, when you can just use a steel nail that will have better durability and avoid jamming. And all of the parts you need can be bought at a hardware store without raising any suspicions. That’s part of what makes this so dumb. They’re not just requiring printers to scan for potential gun parts. They would require printers to scan for anything that could potentially hold or manipulate gun parts. And that is a much broader spectrum than simply scanning for the shapes of the parts directly.
That makes a lot of sense. If the print just holds the critical parts, forget it.