I remember a year ago seeing a lot of ideas on the net about how to get better wifi signal from the receiving side, that is, you place Pringles or a round metal mesh near your laptop to receive better signal from a public WiFi hotspot that you have no control over. It was all DIY ideas. By now businesses must have caught up with this and some of them must have made these ideas into products and improved on them, and by now there could be a standard name for these kinds of products. What is the name? If there is no standard name, what keywords do I put to Google to search for these products?
It's called (depending how it works) an antenna or a reflector, and they have been commercially made pretty much for as long as WiFi has been around (they were not newly-invented a year ago when you first looked. I have commercial ones that are over 12 years old, and they were nowhere near the first of their kind.) The DIY homebrew sort continue to be popular with some, since directional antennas have never had the sort of mass-market to bring the prices very far down, so decent commercial ones may seem a tad expensive if you are used to home-grade wireless products, or things made from junk for free. They are also the sort of thing that a careful home constructor can make "as well or better than commercial product" though most probably don't meet that standard.
The greater the amount of gain, the more sensitive they are to small errors in pointing (ie, the fussier to align) which is rather a pain if you are not setting up a fixed link (what they are typically used for, rather than connecting laptops.)