Well, the rattler concept can be applied well to the PMD damper: 9 pockets can house 9 brass cylinder bobs of 3 differing weights. They all fling to the outer pocket wall and bob back and forth in response to accel/decell, and cover many of the frequencies together.
Yea, i designed such for a UAV engine (and did the PMD in parallel
) drafted it, and spec'd out McMASTER Brass for the bobs. Simple machine work, and a cover plate for inspection and a dab of grease. Well, lost interest due to not having a damper problem. Low risk since the "housing" has the diameter and nearly same mass of our PMD damper. A little thicker toward the timing cover.