vintage army green drab wood box w/ soft cover, surveyors tool or instrument case

1940s or 50s vintage wood box with heavy paper cover, a special purpose case of some sort, possibly for survey / map makers tools? It's made like a large pencil box, light in weight, unlined and a little rough, and measures 16 3/4" long x 3 1/2" wide x 2 1/4" overall.