Creating specs for suppliers and producers is generally at the forefront of our thoughts about the activity. But, it's also important to design for our QA friends, too, for inspection.
We talk about what acceptance sampling is all about. We also step through a thought process for identifying and creating design features for inspection using FMEA.
If you don't have an FMEA, then you can still think through a similar thought process and base inspection levels from how critical that feature is to the design.
As we're designing, we can think about how we're going to be testing and inspecting our product against our specs. We may need to adjust our designs on paper to be able to inspect the parts in hand.