Find of the Week -- Wedell & Boers Carpenter's Case!

I took time out from painting and prepping to go to a family run estate sale that was on the way to the antique mall.  The sale was in a 100+ year old farmhouse on almost a hundred acres.  There wasn't much in the house that I wanted, so I went out to a little block building (about the size of a big garage) in the back.  It was the milking parlor and was full of old farm implements and tools I couldn't identify or begin to guess the purpose of.  I got an interesting heavy cast iron bowl that was the water bowl for the cow being milked (the elderly son of the even more elderly farmer told me this).

My greatest treasure, though, is this really shabby suitcase!  It's cloth over wood and has a drop-down side with a removeable tray.  It's really beat up and in poor condition, but so interesting.  It turns out that it's a carpenter's tool case made by Wedell & Boers in Detroit, probably sometime in the late 1910s or 1920s.  I'm going to vacuum it out, figure out how to clean it up without ruining it and get it into some kind of shape.

It's a fun bit of history, even though it will never be in great condition.  Do any of you know what these slats were for?  The leather belts snap over them to hold the contents in -- I'm guessing that they were for the carpenter's rulers, guages or metal files.