NASA is setting up two radiation sensors within the Bigelow BEAM module on the ISS. One will assess the radiation environment for comparison with the conventional aluminum structures used in the remainder of the space station. The other sensor will have 3D printed plastic spheres placed around them of various thicknesses to see how well that plastic blocks radiation.
Plastic structures are in some ways nearly ideal for cosmic ray protection. Most plastics have relatively low mass and low atomic weight. The plastic structures will be printed on board the ISS using the Made For Space 3D printer. The BEAM habitat module has already shown itself to be as durable as the aluminum modules to minor collisions with orbital debris.