This is the kryptonite knuckles used by Batman in injustice 2.
For printing make sure to use a brim and supports everywhere!
I designed this using fusion 360, I first found a top view picture of the knuckles and placed it on the design part of fusion 360. I scaled it to size by right clicking the picture name on the left of the screen. I then used the sketch tool to trace the outline, and specific parts of the object. I extruded this to a good size height, and put chamfers and filets on the pieces in which it seemed needed. It was especially hard to put chamfers on the curved parts of the object, and some edits were needed. I also used the modify > press pull option to put indents in some parts of the object.