How Svend Larsen created the game broads.

 The game broad are made out of expandable foam. Amazing works.

he are cast from negative molds made out of casting sand. The sand is molded in negative in a casting box but in negative, you can see the negative sand mold of one of the trench boards in the pictures as well as a board just taken out of the mold. The box sides forms the outer frame. and the bottom guides the terrain contour so that they match the other boards.

The box is then sealed of at the top with a foamboard, which when finished becomes the bottom of the board. The air between the foamboard and the mold is filled with expanding building foam (the stuff used for window frames) through four holes in the foamboard. A wooden board (with four matching holes in order to make room for surplus expanding foam getting out) is then placed on the box and secured with screw clamps. Then the foam sets.