I realize this is off topic for a ham radio oriented site, but figured it might give someone pause to think... something that I always advocate for.
As some of you may know, I'm a 3D printer. I've been designing and 3D printing stuff for about eight years now, if memory serves, starting out with a couple of Chinese knock-offs of Prusa printers, and then replacing them with a pair of Creality Ender 3 printers. Both these and the original pair were heavily modified and worked fine within their limitations. Yesterday I received and got to try my latest printer: an Elegoo Centauri Carbon. Not only does it come with an enclosure so I don't have to build my own like I did for the Prusa knockoffs, or rely on a flimsy fabric enclosure like I did with one of my Enders (in both cases I had one printer for PLA printing and a second exclusively for ABS and other filaments that require a heated enclosure), but it prints about ten times faster and supports higher printing temperatures than my previous printers.
Now to the gist of the story. I did a couple of test prints yesterday with no unexpected surprises. The new printer supports stuff that makes me leery; it has an internal camera, which may be good, but also supports connecting to WiFi, which makes it more intrusive than good. Most people seem to think everything from your car to your refrigerator (not sure about sneakers) should be connected to the Internet, but I've no use for that nonsense.
Here's where it gets interesting. After finally getting one of my computers running Windows 10 (which also assumes that everyone is and wants to be constantly connect to the Internet), I grabbed one of my print models, just a simple coaster, and ran it through the slicer software that figures out what the 3D printer needs to do to create the object in 3D, then loaded the result onto a USB stick (oh the humanity! instead of beaming to the printer via WiFi I actually had to insert the drive into my computer, upload the file, and then walk it all the way into the next room and insert it into the printer!) and plugged it into the printer.
Apparently the printer does not like the USB stick, since both times I tried printing the file on the USB drive it gave a critical error message and quit. So I removed the USB stick, and was surprised to discover that my coaster file had been copied to the printer's memory, so I tried printing it from there. Skipping ahead (it didn't work), I tried another of the files that came preloaded into the printer's memory, and it printed just fine. But each time I tried MY print, as soon as the printer bed reached operating temperature, THE FAN ON MY INDUCTION COOKER IN THE NEXT ROOM STARTED CYCLING ON AND OFF WEIRDLY. The fan is temperature controlled, but it wasn't just going on and off; it was essentially doing a little jig, for lack of a better explanation. Meanwhile the printer went off into lala land with the bed raising and lowering and the control panel frozen.
Here's the real kicker: Both the printer and the induction cooker are on a circuit powered by an inverter, rather than one connected to the utility grid. Perhaps it's my background as an investigator that makes me jump to conclusions, but I'd be willing to bet that if I plugged the printer into a grid-connected outlet the problem would disappear, because based on what I know about electronics, I'm pretty sure that the printer was trying to communicate through the electrical circuit (not realizing that it was a closed circuit) and ended up talking to the induction cooker instead of whatever it intended to, resulting it to go into a don't care state (a TTL electronics term that describes a situation where stuff stops responding to input).
What's the common denominator? Both the induction cooker and the 3D printer are made in China. Imagine, if you will, not only the amount of data "they" (Hey, could be our own NSA for all I know) could amass by having such devices report back to them (If you haven't heard of, for example, laser microphones that convert vibrations in windows to sound, letting you hear what's going on in rooms with windows, you probably don't realize that almost anything connected to the outside world, either by wire [utility grid, phone line, cable TV] or wirelessly, can be used to spy on you), but how fun it would be if these devices were controlled remotely!
So I guess I'm gonna have to invest in another oscilloscope and some other high-tech analysis equipment and see what's really going on here, but as I alluded to above, the minute WiFi came into the picture I got a bit leery. Moral of the story: if you use any electrical devices more advanced than a can opener, you might want to consider them "hackable", both as monitoring devices and as potential weapons that could be used against you.