Credit cards are a popular payment method, especially for business transactions.
Sometimes, high-value business transactions require the approval of more than one person.
Additionally, if a credit card is lost or stolen, someone will have to meticulously verify that no fraudulent transactions were made on it, which can be very time-consuming!
Both of these problems, and more, can be solved by physically cutting the credit card up into multiple pieces.
Each piece would be held by a different individual, and the card would need to be re-assembled (like a jigsaw puzzle, as in Figure 1) prior to any transaction.
With this “jigsaw puzzle credit card” system, any transaction will be physically impossible without getting the approval of all card-piece holders, thus removing the need for complicated reimbursement systems involving people signing off on business expenses.
As an added benefit, if only a subset of the credit card pieces are stolen, the card will become unusable and the thief will be unable to make any unauthorized transactions.
This would be useful for both business travels and individual users who were, say, traveling to a foreign country with their friends or family.
It would be possible to make cards in many different styles: for example, a card could be split into only two pieces, or as many as 8 or so before it started becoming impractical.
PROS: Facilitates commerce! Also works with debit cards, ATM cards, library cards, etc.
CONS: Each piece’s unusual shapes would make it difficult to fit into a wallet. Perhaps each piece could be slotted into a plastic “dummy” credit card, thus maintaining wallet compatibility.