Patterns are everywhere! Their regularity is both fascinating and intriguing: if from an aesthetic point of view we are pleased when admiring them, from a mathematical point of view we want to explain this regularity. In this talk we will shed some light on mechanisms behind pattern formation. In particular, we focus on the formation of a single shape. We work in a variational framework, namely we view patterns as configurations having least energy. The optimal shape will then be the compromise of the effects of competing forces. The prototype is having an attractive and a repulsive force. We will consider several variants of such terms having different features, and investigate how this affects the optimal shape. This talk is based on a series of works with Marco Bonacini (Universit\`a di Trento), Maria Giovanna Mora (Università di Pavia), Lucia Scardia (Heriot-Watt University), and Ihsan Topaloglu (Virginia Commonwealth University).