From things I've read on Steve Jobs, he seems equally interested in the industrial of building the products he designs[1]. I've also heard their lead designer Jonathon Ives talk a lot about materials and how to use them, which I think underscores the fact that he is an industrial designer, meaning he doesn't just design an end product, but also designs the process, or at least designs the product with process holding equal weight with the actual aesthetic.

I've also read that they require all parts to be doubly sourced, so that if one source fails, they have a backup. I don't know how common this is, but seems like an interesting point in their process.

[1] He doesn't design them himself, but I couldn't think of a better word.