Wise decision. Especially if it is a debit card instead of a credit card. If I remember correctly, the former does not have all the protections that the latter does, regardless of whether or not there's a big credit card company's logo on it.
Glad you found your $100. As art, they're not very pretty, lol - but useful things nonetheless. I used to hide them everywhere (back when I actually saw the things on a regular basis
) . The glove boxes on most of the cars I've owned were pretty easy to open "too far," so I tended to tape a couple to the back for emergency gas (etc.) money when I was off camping or some other activity out of town. And around the house, whew... I once had to go back into a rental (with owner's permission) and pull the roll-up blinds down past the bottom of the windows so I could grab the ones I'd rolled up into the top of them. No thief ever looks there, lol.
Mom used to hide them in random hardback books on the living room shelves and elsewhere around her house. That one came to a stop after she figured out that she'd stuck one into a
library book
. Luckily, it was still there when she went back to the library a week or so later to check. She actually found a "straggler" a few years after Dad died. Made her a little sad for a bit; they could really have used it, not just toward the end of Pop's lifetime, but years before when they almost lost their house. But it sure came in handy when she found it.
Money is easy to hide, especially the "paper" kind. The inside of toilet paper rollers often works, depending on how fancy said device is (the simple hollow tube being best). Possibly not the most sanitary idea in the world, but probably secure against theft.