IKEA is well known for its easy-to-assemble products. The company recently introduced a further innovation in this regard: assembly without tools.
While not everyone will agree, most people actually do find it easy to assemble IKEA furniture. Nonetheless, a common complaint is that the tools that IKEA provides are cheaply made and not very ergonomic (i.e., they hurt to use).
IKEA therefore decided that tools oughtn't be necessary, and set about removing the need for them. The result is a new line of furniture called Regissör (see figure 1 for an example). While it's outward appearance is fairly typical for IKEA furniture, it's quite different when you look at the pieces.
Exercise for the reader What do you think the basic requirements of this type of product were, as IKEA conceived them? Why do you think such a product might be well-received by IKEA customers?
You can see pretty much the whole system at work if you look closely enough. Notice the weird geometry of the “peg” on the left piece. You can also just see a slot in the right piece, into which the peg very obviously mates.
Exercise for the reader
Finally, here are three videos about Regissör. The first is IKEA's own video about the furniture line. Parts of it are in Swedish, but you can get a bit of insight from the English parts.
The second video is from Business Insider, who managed to get three utterly incompetent people to try to assemble Regissör bookshelves. That a manager would pass judgement on the “structural integrity” of an engineered product - probably because he was the only one wearing a tie, which naturally makes him an expert - is rather blatant misrepresentation.
The third video is by someone with the (rather basic) skills to read instructions and follow directions like a reasonable, thoughtful human being.