Just a small project iconography project here. I made three Flesh Tearers icons in different sizes all using the same approach. I started by taking a small ball of Green Stuff and flattening it into a smooth round disc. Then I took a plastic circular rod and made indentations around the edge. Finally I cut away with a sharp scalpel a small amount of Green Stuff on the edge of each indentation and cleaned up all the edges with a needle point.
Quite simple in theory, but it does require a steady hand.