For the rivets, some very thick paint in the color you need would do very well. You would be adding very little, but the thickness of the paint would make it so that if you ran your hand over the rivets, you could feel them. I dont think that the pinheads are a bad idea though. I just picked up a box full of abotu a bajillion pins, and it wasnt that heavy. At most, with the pinheads and glue, you would have about the wight of 2 standard servos. You have to remember, you are only using a very small protion of the pins themselves.