I have some cool plastic knuckles for sale. 1/2 once and sturdy. Non-Metalic.
$10 each shipped (BLACK)
$12 each shipped (TAN, BRONZE, PINK/GOLD SWIRL)
Note: These are 3D printed. On these the longer spikes on the ends don't get printed well, I've posted photos below of typical imperfections. They still will work for there intended purpose, they just don't look pretty. They can be sanded down pretty easily if they are not wanted.