We address the problem of propagating a piece of information among robots scattered in an environment. Initially, a single robot has the information. This robot searches for other robots to pass it along. When a robot is discovered, it can participate in the process by searching for other robots. Since our motivation for studying this problem is to form an ad-hoc network, we call it the Network Formation Problem. In this paper, we study the case where the environment is a rectangle and the robots' locations are unknown but chosen uniformly at random.We present an efficient network formation algorithm, Stripes, and show that its expected performance is within a logarithmic factor of the optimal performance.We also compare Stripes with an intuitive network formation algorithm in simulations. The feasibility of Stripes is demonstrated with a proof-of-concept implementation.