A radiation beam field shaping device is made from a 3D printed frame that contains and gives shape to a granular material with bulk density of at least 3 g/cm3 and composed of metal grains having a size between 1 μm and 4 mm. The frame has a hole in the bottom with surrounding walls that defines the desired beam shape. In one implementation, the metal grains are composed of solid tungsten alloy ball bearings and/or tungsten alloy powder.
