I would think all of thing things we associate with being a hipster. Those things are what attract these people and we later just called them hipsters to categorize.
Hipsters aren't non conformists. They are conformists. The whole culture is the act in conforming to be like other hipsters.
There are very few people that make their own clothes from raw material, people have to buy the cloth or the clothing itself from somewhere. Of course this tends towards clustering as the mainstream is by definition pretty broad, so it is visually easy to group together "people who wear weird/retro/custom clothes and hair styles" together.
Yet if you polled hipsters, I'd bet a wide diversity on other opinions/tastes in music, art, film, issues.
This goes for many sub-cultures, from goths, to metal heads, to punks, to yuppies or Bobos. Everyone mixes non-conformity at some level with conformity, especially when they link their tastes and opinions with their identity.
Hipsters just happen to want to be identified for their non-conformity which is what makes them annoying to many people, as this rejects the value of a thing based on its relative popularity.
We've seen elements of this in the past with Rock music fan's accusation of "sellouts" which is somewhat unique among music genres but makes total sense when the identity of being "Rock", for a portion of the fan base anyway, is to be in rebellion against The Man (with money and power).
Hipsterism just takes this to the next level, valuing the relative obscurity of a thing above all other qualities. Except with the Internet, it's easy to find obscure things and popularize them... Among hipsters anyway. Leading us back to clustering.