I remember sending flash cards was quite popular years ago. Never thought it was cool, but as a person living far away from family, also as knowing the USPS never delivers my mails on time, here I decided to design a flash card. 
The concept is simple: something that says hi to my family and good friends with a little thing to play with - which will hopefully help them understand what I do for living. (They never get it.) Colors were derived from the year-end holiday theme colors but toned down to emphasize bells.