Actually, they're great for holding any type of card.
The one above was made with a vintage silver plate lid. I gave it a weathered white finish, with a touch of rust, and, used vintage wire for the holder. Yes, I have miles of vintage wire.
This next holder came about when I thought of something to do with this bag of vintage porcelain and metal flowers. I salvage these pieces from a broken wreath I purchased at a thrift store a while back.
I used a salvaged metal lamp part for the flower pot, and, added a flower, leaf, and, my wire holder.
Quick setting cement holds the three elements in, and, paint unifies the whole.
I have a bunch of flowers left, and, lots of lamp parts. So, I'll be making a lot more.