(Cost plus a $30-$80 battery, of course, but after you pick your color, you've already got batteries). Your locks are far more protected by the social contract that would compel a stranger to stop someone who was cutting a bike lock with an angle grinder, and would cause a thief to fear arrest, prosecution, and jail time, than by actual physical security.
If you want a laser, you can already get a 100W CO2 laser tube for $500:
It won't do a great job of cutting steel - it will engrave it, but to cut steel you'd need O2 assist gas and a lot more power. It will trivially cut ABS, foam, fabric, wood veneer/thin plywood, cardstock, etc. if attached to a pair of mirrors on an XY stage such as might be borrowed/scaled up from a 3D printer. And, of course, it will trivially scar corneas with the invisible danger of its 10,600 nm laser light. Good news, though - ordinary polycarbonate safety glasses are opaque to the extreme IR light.
Laser safety is serious business, but highly-collimated, tightly-focused laser light is not likely to be produced by a cheap, portable laser. The above tube produces a 100W beam with a diameter of about 8mm. I wouldn't put my eyeball in the path, but a safety shutter can sit in the beam indefinitely and merely get warm. You melt steel by focusing a this 8mm beam down to a infinitesimally tiny spot, and beyond the focal length of your optics it diffuses to something no more dangerous than the source 8mm beam, and beyond that it's no more dangerous than an average lightbulb - albeit one that you have no aversion response/blink reflex to. I always wear my goggles near our cutting lasers, but I know lots of guys who have worked around 20W-20,000W CO2 lasers their entire lives and they're pretty cavalier with regards to laser safety.
Finally, a welding mask is a neutral-density filter, suitable for the (very approximately) black-body radiation produced by a welder, and is much less effective than laser safety goggles at blocking high-intensity light of a very specific color. Depending on the sensor, an auto-darkening mask might not even trigger when exposed to a laser! You'd want a set of 940nm laser safety goggles for this, which is far more exotic and dangerous than a 10um CO2 laser.
Don't cut vinyl with your laser, it will produce chlorine gas which will not be good for you to breathe and will corrode your equipment. Use a dragknife cutter instead.
It does work, and I've got great filtration and ventilation, but yeah, probably not a good idea. Edited. Same caution is true of PVC, which is a shame because it's really convenient for making the aforementioned ventilation systems!
A question I've always had: How do I know if my glasses protect against a particular laser? I'm talking about the ones in hobby CNC machines, laser hair removal places, etc, not high-powered industrial ones, where there's likely a high degree of know-how on safety already?
Best bet is to buy two pairs and stick one in the path of the beam with a sensor or target behind it. Otherwise you're looking up charts for the materials spectral absorption in your lasers emission band
But even if the target isn't cut, that doesn't mean I won't get eye damage, does it? Or do glasses protect even if they're only a bit opaque to the target wavelength?
First of all, I take no responsibility for your safety, I'm just some person on a forum.
That being said, it's all a function of how much light enters your eye. You can look up the exposure limits of the human retina for different frequencies of light to get an idea how little is actually required to damage your eye. The target or sensor should be sensitive enough to react to that much incident light. Just putting something behind the glasses and have it not get cut is definitely not enough to indicate no eye damage.
Proper laser goggles come with ratings. Dependent on the laser wavelength, beamsize, energy/power and pulse duration. Most goggle suppliers will tell you what you need if you supply the laser specs.
A long while ago, I was told that the flight deck crew on Air Force One would wear eyepatches during nuclear drills, so that if (hopefully temporarily) blinded by an airborne nuke, would be able to continue flying after switching the eyepatch to the other eye.
https://www.harborfreight.com/power-tools/grinders/angle-gri...
(Cost plus a $30-$80 battery, of course, but after you pick your color, you've already got batteries). Your locks are far more protected by the social contract that would compel a stranger to stop someone who was cutting a bike lock with an angle grinder, and would cause a thief to fear arrest, prosecution, and jail time, than by actual physical security.
If you want a laser, you can already get a 100W CO2 laser tube for $500:
https://www.amazon.com/Cloudray-W2-Dia-80mm-Engraver/dp/B08G...
It won't do a great job of cutting steel - it will engrave it, but to cut steel you'd need O2 assist gas and a lot more power. It will trivially cut ABS, foam, fabric, wood veneer/thin plywood, cardstock, etc. if attached to a pair of mirrors on an XY stage such as might be borrowed/scaled up from a 3D printer. And, of course, it will trivially scar corneas with the invisible danger of its 10,600 nm laser light. Good news, though - ordinary polycarbonate safety glasses are opaque to the extreme IR light.
Laser safety is serious business, but highly-collimated, tightly-focused laser light is not likely to be produced by a cheap, portable laser. The above tube produces a 100W beam with a diameter of about 8mm. I wouldn't put my eyeball in the path, but a safety shutter can sit in the beam indefinitely and merely get warm. You melt steel by focusing a this 8mm beam down to a infinitesimally tiny spot, and beyond the focal length of your optics it diffuses to something no more dangerous than the source 8mm beam, and beyond that it's no more dangerous than an average lightbulb - albeit one that you have no aversion response/blink reflex to. I always wear my goggles near our cutting lasers, but I know lots of guys who have worked around 20W-20,000W CO2 lasers their entire lives and they're pretty cavalier with regards to laser safety.
Finally, a welding mask is a neutral-density filter, suitable for the (very approximately) black-body radiation produced by a welder, and is much less effective than laser safety goggles at blocking high-intensity light of a very specific color. Depending on the sensor, an auto-darkening mask might not even trigger when exposed to a laser! You'd want a set of 940nm laser safety goggles for this, which is far more exotic and dangerous than a 10um CO2 laser.