Marketed by who though? Like the article says, there is no main company or companies behind this. Just lots of random products cheap from China being resold.

I wouldn't be surprised if some smart folks in China launched a covert social media campaign to sell this stuff. You don't need much (aside from money and some dedication) to create a fad these days, as long as it's something simple and doesn't require extensive concentration to grasp.

They have been popular with folks that owned 3D printer for a while. It could be something simple like a critical mass of 3D printers being reached. My wife was printing these for fun a few months before it all exploded.

There are ads all over Facebook and Instagram

Why on Earth do people not run ad-blockers on Facebook and Instagram? I never see ads on either of those sites.

Lots of people don't know how to use browser extensions.

Some people don't like to use many browser extensions, like me. I've never been bothered by the ads; sometimes they are even useful.

>I never see ads on either of those sites.

Half of the content of both of those sites is ads, even if it poses as part of the regular flow (sponsored feeds etc).

another? what is the other one? the yo-yo?

"another? what is the other one? the yo-yo?"

Lemarchand's Box:

https://en.wikipedia.org/wiki/Lemarchand%27s_box

Folding/Butterfly knives?

ive never seen an ad, only self reported use/pictures. The success is in hitting a nice intersection of cheap/satisfying gadget.

Well if you have seen someone using one on Instagram, it's an ad if that person has more than a few thousand followers.