A unit is an abstraction. A meter is less abstract. The last meter of your driveway even less abstract. How I would measure each depends on how abstract it is.
Physical properties can be purposes. A purpose is simply the reason for existence. And if the reason for existence is because of something's physical property, then the physical property is its purpose. An example is.. bricks. Bricks are not natural, they are man made and exist because of their physical properties; properties obtained from failed attempts to create bricks, or as a result of using other materials that did not exhibit those desired physical properties. So the purpose of a brick is to be a brick, which is a physical thing, with physical properties, not an abstract thing.
Right there my point was that your reply asking what units a unit is measured was exactly the same as the original question of how one measures or quantifies "purpose" if it is not an abstraction. A weapon is anything designed or used to inflict harm or damage. "Used' is obviously the part that is relevant to us in this conversation. There is no point. You are a strong believer in the 2nd amendment as you interpret it, but think it doesn't cover the creation of arms. I'm not so sure, and if true then it is useless.
So if a purpose is because of something's physical property, then the physical property is its purpose? So a brick is hard and resists being crushed. I can think of many purposes for such a physical property, or most any physical property.
It is not useless. Not at all. Because commerce would be regulated, and that individual states would dominate that regulation, there would be very very few things government would stand in the way of being made, especially with a business decision. Then the courts decided that intrastate commerce was actually interstate commerce, because anything made internally meant something would be purchased externally, thus affecting interstate. But even still, how likely do you think the government is say firearms cannot be manufactured? They didn't even say it when the Federal "assault weapons" ban went into effect; they said they couldn't be sold. They still made a shit ton of them, for law enforcement and military use. The government will rarely, if ever, ban the creation of something. It can't, or very very rarely, be imagined now. Why would you imagine it could be then? Even nuclear weapons, we don't ban the creation. We just heavily regulate who, what, when and where can do it. And if we don't ban the manufacture of that, what are we willing to ban? So if it can't be imagined, why does it need to be included? The answer is it doesn't, that's redundant.
There are many purposes, which is why intent was also included. But purpose isn't abstract. The thought of the purpose is abstract. Once you put it in to effect, you've created reality, and thus no longer abstraction. If you imagine a brick to be an airplane. That's abstract. When you make a brick fly, now its real.
And yet the NRA and others don't challenge the banning of 3D printing firearms for fear of broader manufacture bans?
They have challenged and challenged and challenged and they cannot beat this law on a 2A challenge. So why would they continue? They know they don't have a 2A defense. What defense does that leave them? https://www.atf.gov/firearms/qa/does-individual-need-license-make-firearm-personal-use
And yet you called it a brick and not an airplane. An airplane isn't a purpose, anyway. If you think the purpose of a brick is to successfully travel through the air, the physical properties of the brick remain the same as when you imagined the purpose to be a building material, a weapon, a doorstop, etc. So physical property isn't the purpose.
When it is turned into an airplane, it is an airplane. Until then, its purpose is its base purpose, or resting state, if you ill. Aerodynamics is a physical property.
Yes, I do. Your example is difficult for me since it doesn't seem plausible to my apparently limited intellect. Sorry I am too dumb to understand bricks that become airplanes