I make a lot of marijuana paraphernalia (stash boxes, rolling trays, pipes) all from wood. Its a great stress reliever (the wood work, not the weed - never mix the two), and people love them and buy them.
With each new product, I try to add a new skill to it. So for my stash boxes [1] (I've only made 3 so far -- all prototypes), I have an "air-tight" lid that requires being within 0.001-inches, and the lid incorporates a rolling tray on the underside, so you open it, flip it over, it reseats inside the box, and you have a stable tray to grind you herbs and roll a joint. I haven't figured out mass production on it yet, though, so each one takes me about 2 hours of work, and none of them are perfect, but that is the fun part of it. Figuring out how to make something is easy, figuring out how to make it more than once and quickly is a challenge.
It's 1/thou, not 1/10k. 1/thou is within a couple thou of the maximum difference in expansion.
How I keep my wood from over expanding and shrinking is by using aged woods. My red cedar (what my stash box is made of) was cut down multiple years ago and stored at my grandfathers sawmill, it was then milled 2 years ago to 3/4 rough. I hold them in my shop for over a year before I plane them, then another 6+ months before I use them. All that time, the moisture has stabilized (theoretically), so the only expansion and contraction would be through temperature, which has a much smaller effect than moisture.
I have had some of my wood products expand in shipping, but after a week of them sitting in a person's home, they will be back to normal. That was my vape cart holders. So after a few people said when they arrived they couldn't use them. I started milling them a little looser.
With each new product, I try to add a new skill to it. So for my stash boxes [1] (I've only made 3 so far -- all prototypes), I have an "air-tight" lid that requires being within 0.001-inches, and the lid incorporates a rolling tray on the underside, so you open it, flip it over, it reseats inside the box, and you have a stable tray to grind you herbs and roll a joint. I haven't figured out mass production on it yet, though, so each one takes me about 2 hours of work, and none of them are perfect, but that is the fun part of it. Figuring out how to make something is easy, figuring out how to make it more than once and quickly is a challenge.
1: https://instagram.com/p/CvpUKVBLph3/