The first Swedish made box that l have seen so far is made in 1942, and that is also the year for the oldest Swedish produced case l know of. This makes me believe that the first years of production is imported, from Germany, Finland and USA. These countries are represented in the AMKAT catalog of 1944.
The first kinds of boxes is containing 50 rounds, and can be found in some different typed. The first ones is an open lid type with or without supporting walls around each round.
The later kind of 50 over box is a one with a short wall opening containing a drawer with supporting walls around each round.
The later box introduced around 1955, l think, is containing 36 rounds mounted on a supporting bracket of steel. The steel plate is for the speed loader made for a very fast
loading of the 36 round submachine gun m/45 mag.