These mount brackets are for Premier Signia tom drums. They are the black plastic parts that sit between the mount.
PETG is HIGHLY recommended as the part needs the ability to flex some but still be sturdy. Other materials may work but use at your own risk. I print these parts vertically, up on end, and use supports for the internal overhangs.
I have many drum parts available for sale, if you would like to browse more of my items:
The author marked this model as their own original creation.