I designed Mathematical Furniture in 1995, using only circles and straight lines. The design process is rule-conducted and I call this way of working FORMULA, which in Latin means beauty, rule, guiding principle. In Mathematical Furniture, I describe the design of a Euclidian family of furniture. The design includes a table, a chair, a cupboard, and three transformations of the ensemble. In A group of elliptic tables, I describe the design of a series of tables with a large number of possible leg positions. Due to lack of space, some illustrations are not included here but will be shown during the presentation of the paper (Figures PP).