It's a fun toy for playing with the dogs though, or shining a line 15km across town in the dark onto tower blocks. I really can't imagine any other legitimate use for it...

It's true that you almost certainly don't need it. It's somewhat too weak for cutting, would have to be about 50 Watts minimum (Watt, not milli-Watt). If that was the case, I'd yell out: "Go build a cool CNC!".

But it's not just about really needing it, it's also a bit of a matter of principle for me, too. It's the same moronic reasoning as always. So there are 3 or 4 jerks who are trying to bring an airplane down. They can be caught easily enough, but what happens to them when they're caught? Nothing. Are they sentenced 3,000 years of prison for attempted murder in 300 cases? No, of course not, those ultra-left judges wouldn't do that ^[1]. People who try to kill innocent people need to be resocialized, not punished.
Instead, they make the lasers illegal for everybody, including you and me who might indeed have a legitimate use for them (whether you do or do not is nobody's business but your own, as long as you don't hurt anyone). And then, at the same time, you can easily buy lasers which are a hundred times stronger, unregulated and unchallenged.


^[1] While "life sentence" equals 15 years (WTF?) and an average sentence for murder is 10 years, which is already ridiculously little, I am aware that it's even worse in other countries. I was rather shocked to see on TV news yesterday that the president of France reprieved a woman who had murdered her husband because of some sad story involving domestic violence after little over one year in prison. Domestic violence is no fun, but be that as it may, shooting someone into the back three times while he is asleep can hardly be called anything but murder, can it (you surely can't call it self-defence, even if the victim is a violent snorer).

And then, at the same time, you can easily buy lasers which are a hundred times stronger, unregulated and unchallenged.

Yeah, I've always been curious about that. The reason they're not so concerned I think is because these bigger lasers are non portable, mains powered and not something you can carry in your pocket on a night out to the airfield or to a football game (there were many cases of idiots trying to blind sports players too)... As always the idiotic few ruin things for the sensible ones like you and I...

The reason they're not so concerned I think is because these bigger lasers are non portable, mains powered and not something you can carry in your pocket on a night out to the airfield or to a football game

They're not necessarily that big. Which is why I'm wondering.

There's people who use the step motors from DVD burners pulled from the trash can to build an x-y mechanic, with an Arduino reading G-code, and they use the drive's laser diode for scorching images into wood or onto paper. Works surprisingly well, plenty of youtube videos showing. The diodes reportedly have 200-300mW. Which, compared to a <1mW laser pointer is... bummer. They're how big... under one centimeter? Powering them with a couple of batteries (2 are probably enough? 3V?) shouldn't be an issue either.

I don't know how powerful the newer, stronger M-Disc capable diodes are. But you can about figure since the difference in power consumption between reading and writing is somewhere around 15-18W. That's Watt, not milli-Watt. I'd guess you can probably use that for a CNC that doesn't just scorch wood, but one that actually cuts through reasonably thin material. And, well, of course... it's way enough to permanently blind yourself or anyone within a kilometer or so if the ray accidentially hits an eye for a fraction of a second...