My mother did baking, wedding cakes, etc. for 20 years, so if I remember I will ask her when I talk to her.
I would check local "dollar stores", Over the Hill sections, party supply stores (our local one is 50-50 party supply), possibly Walmart too. I've seen them, don't remember where. I really thought they would have been more common.
black and gold
black laser cut wraps
brown foil cups
Also found more than a few disturbing sites like : Black Metal Cupcakes are made with 2 cups of the blood of the innocent, drawn at midnight when the moon is in the sign of the goat.![]()