I remember discussing on twitter whether goods that have a fashion aspect are in the custom-built phase or not. The topic is important, because we, humans, are concerned with status, power and displays of those.
Fashion and personalisation are means of ‘expressing yourself’. Some people claim it is all about individualism and standing out from the crowd, but some other - recognise the same behaviours as attracting attention (to increase your chances to find a desired romantic partner) and reduce effort put in conflicts - as individuals may resolve it by judging the book by the cover.
Naturally, those displays of status are environment specific. It takes an entirely different approach is used in different communities. Some rely on physical force and vitality, and in those communities, everything that exposes those traits will be in demand. In some other groups, a particular skill defines the status, so everything that shows the skill will be desired.
With that understanding, everything that is related to fashion looks like at least a product or even a utility in the Wardley Mapping sense. Those means of expression have to be ubiquitous to work; others have to be able to understand the message, because, without that, you are failing to communicate who are you, and you become a weirdo (which, in turn, may be the desired message if you are in the group of eccentrics).
That state would not change much, were not it for our desire for novelty. Existing evidence suggests that we are curious by nature and that some of us are more curious than others, but also that this curiosity is quite limited. We love familiarity, but with a twist, and finding the right twist is the core aspect of creativity in the fashion industry.
The new product must look familiar and feel novel for the majority of people. Otherwise, it will not become ubiquitous. There is still no custom-built element, despite the apparent volatility of the fashion industry.
More, the process of creating such familiar items with a right twist is highly industrialised. Fashion researches can predict what will be hot long time before it really becomes hot by observing how people behave, and how they break existing rules.
There are the true custom-built elements. People, expressing themselves, experiment, and new trends emerge. The role of a researcher is to spot that trend and amplify it. Naturally, not all trends become truly ubiquitous.
So, from the perspective of a consumer, fashion is highly industrialised. People are expected to stick to the rules of their environment if they want to communicate well, but people also break those rule on purpose to get the feeling of novelty.
It is a paradox. What looks like being in a custom-built state, is in fact highly industrialised domain, with the small, almost negligible, part of emerging behaviours.