Even if my fingernails are no longer brittle, it is still painful to use them.
To open a pop-top can I use the bowl of a spoon.
To open a shaker with a flip lid, I use a plastic (invalid) charge or customer loyalty card.
I also use the card for the tiny switch on the bottom of an electric candle or snow globe.
Also to open the battery chamber for those kinds of things.
Also to scrape the label off a container so I can use it for other purposes.