A tato is a Japanese container that lies flat. They tend to be symmetrical. Letter folds are meant to contain a message, and envelopers are containers that are usually sealed after use. Tatos are meant to be reusable. Through the ELFA mailing list and my own research I have found how to build tatos for three to eight-sided regular polygons. Most instructions for a triangle start from a triangular piece of paper. I found a way to do it from a square.