This model is of Thor's Cape Brooch and chain from God of War Ragnarok, used to hold on a cape or cloak.
The brooch has a recess underneath which allows for the brooch pin to be inserted and twisted. This can then be attached to clothes with a safety pin and the chain will be held between the clothes and the brooch.
I have added different lengths of chain to suit different sizes of costume.
Print the brooch and pin twice and the correct length of chain once. I found these printed without supports or a brim, though your printer may need a brim on the chain if you suffer from bad adhesion at times.