It seems that automotive toolboxes were generally fabricated from metal
yet machinist toolboxes seemed to be predominantly wooden? Why the difference? I would think wood would be more prone to retain mositure and be a source of corrosion than metal. Is it one of life's unsolved puzzles?
It depends on the era you grew up in. When I started in the trade, the machinist box of choice was the brown Kennedy's. The old timers that I worked with had Gerstners. Today, a machinist or Toolmaker may have anything.
One thing about a machinist box over a mechanics box is the gap between the drawers. If you look at a Kennedy top box, say a 521 or a 526, there is not a lot of space between drawers. If you look at a similar size mechanics box, chances are you can see in the drawers due to a wide gap. I think a lot of the tighter gap of the machinist box has to do with keeping swarf out. Also if you look at a machinist box, the drawers are way smaller in height than a mechanics box. Most machinist tools are not very large as far as height goes, hence the reason for the narrow height of the drawers. Also a machinist box doesn't need to carry the weight that a mechanics box does. Although, I was a different toolmaker than most, and I made use of the deeper drawers on my boxes. I kept things right at hand instead of running here and there to try and find something.
When I started in the trade, I bought Kennedy's. When I ended the trade, I had a large Crapsman top box, and a Menards base.
I've had numerous Kennedy boxes over the years. I've gave away some top boxes to ones that may have really needed one to start out in the trade. I've sold a few to different ones, and I still have an 8 drawer top box and a two drawer intermediate, and I have another that I repainted in black wrinkle. A coworker and good friend that I was training to become a toolmaker was not really loaded with cash, so I sold him my Kennedy setup (Top box, intermediate box, and 7 drawer roller) to get him started in the trade for the whopping total of $125. And it was all like new. That's how I ended up with the Crapsman and Menards setup.
As far as Gerstner boxes, that was sort of a stature thing among toolmakers. If you had a Gerstner on your bench, everyone knew that you were a toolmaker and had been in the trade for a number of years. Gerstner is looked at as the Cadillac of toolmaker boxes, and is more like fine furniture than just a toolbox. Of all the different boxes I've had over the years, I never did have a Gerstner box. I may get one someday, but not anytime soon