We consider the formation of small-scale magnetic structures in solar coronal loops, with the aim of understanding the possible role of these structures in the process of coronal heating. A simplified model of a coronal loop is discussed. Neglecting loop curvature, we consider an initially uniform magnetic field embedded in a perfectly conducting plasma between two flat parallel platesz=0 andz=L, which represent the photosphere at the two ends of the loop. Slow, random motions at these boundary plates produce twists and braids in the magnetic field. We discuss the properties of such braided fields assuming the field evolves through a series of force-free equilibria.