During development, tissues are pushed, pulled, and folded into complex shapes. The brain begins as a flat sheet of cells, called the neural plate, that folds into a neural tube. The neural plate has a network of force producing filaments on its surface that helps fold it into the neural tube. To understand how the network promotes neural tube folding, we’ve created the first high-resolution images of the filaments across the surface of the folding neural tube. The pattern of filaments we observe have allowed us to build a model of the mechanics necessary to fold the neural tube in mammals.