This is a substitute shinigami badge from Ichigo Kurosaki in the manga named Bleach.
I found some dimensions on a website but they aren't not good for me so i design my own badge. I use it for cosplay or decoration.

I made a wood version first with MDF : 12mm thick, 6mm thick and 3mm thick.
12mm is for the big part, 6 for the upper edge and 3mm for the detail (skulls and cross).
Not so easy to cut the small part with tool !

I made this new version in PLA with my 3D printer to compare the two.