Letters for you / a public welfare plan based on local supermarket

Letter For You is a public service design based on local supermarkets. The coating of the product label gradually disappears with time, revealing the underlying letter. Customers can donate public goods exchange letters(mails) by collecting the corresponding letters(alphabets) on the back of the shopping receipt to help the poor, which encourages people to buy products with old dates.
It could reduce the Food waste causing by Expired. Supermarkets and dealers can also make more profits, and take some of the profits to provide free materials to help the poor. Also, the collecting game make the customer's shopping journey more interesting.