Will do!. Density of the physics material… okay… My bridge was a rope bridge, made of planks, each plank connected on each side by physics constraints in a similar way to your own setup. I made each plank a blueprint actor, and added a trigger volume on top of the plank. My thinking was that when a character entered the volume, it would increase the mass of the plank, when the actor left the volume, it would be reset. I couldn’t find a way to change mass scale dynamically, but I did find link text which showed another way to achieve the same end. So I added a float variable to my plank blueprint, and in the construction script set it to the density of the physics material. Then, on entering the trigger volume, it sets the density to that variable multiplied by 1.5, and on the exit of the trigger volume, sets it back to the variable with no multiplier. Therefore as I walk along the bridge, as I step on each plank it becomes 50% heavier.