I saw this post on twitter:

It talks about the mechanical tolerance for LEGO, which is literally bonkers. Like, VERY EXPENSIVE MECHANICAL PARTS typically have nowhere near this level of tolerance.

I actually have to OVERSHOOT the size of the mounting holes, because the tolerance of drilled hole size at JLCPCB are "+0.13/-0.08mm". 0.0005 inches is 0.0127mm. This means that I need to make the mounding holes 4.9mm instead of the "precise" 4.8mm, because if I designed them to be 4.8mm in diameter, they could be as small as 4.72mm, and the 4.8mm of the lego peg sure as hell isn't going to change, it's only allowed to be in the size range of 4.7873mm to 4.8127mm!