Apple Releases Detailed Apple Watch Drawings to Public [PDF]

This seems like a surprising level of openness for Apple. This document is targeted at custom band/case manufacturers. I'm fairly certain that similar iPhone/iPad specs have previously only been available through very closed programs.

I'm unclear though, on whether you can make your own lugs. Historically, Apple has allowed 3rd party accessories, but has effectively charged a licensing fee by requiring the purchase of enabling hardware (30-pin connector, Lightning connector, Authentication Co-processor). I'd assume Apple wants you to buy Apple lugs, but it's unclear on whether Apple's lugs are a requirement or a convenience.