When I send out mail art, I like to send a "package" of bits and pieces. Normally there is a postcard sized "main" collage, but I also like to include the odd ATC and things like this that I call my mailart bits. These are usually created as a result of me playing and indulging myself and having a bit of fun. In South Africa, the lucky packet has been a phenomenon for years. They consisted of a paper packet (nowdays plastic) containing a couple of cheap sweets, maybe some sherbet and a couple of cheap plastic toys. I hope that my mail art "lucky packets" generate that same experience of surprise and fun and entertainment that I remember from my childhood.
