Methods of preparing a three-dimensional structure are provided. One method includes the steps of extruding beads of thixotropic thermoset materials, and subjecting the beads to curing conditions such that the thixotropic thermoset materials at least partially cure to form cured polymer layers. In some cases, the curing conditions are not applied until multiple beads are extruded and in contact with one another. The steps of these methods can be performed repeatedly as desired to prepare a three-dimensional structure of nearly limitless shapes by additive manufacturing processes. Thixotropic thermoset materials are also provided, as are three-dimensional objects formed therefrom.