Current immersive modelling environments use non-natural interfaces to support traditional shape modification operations. In the future, we expect that natural interfaces will become the typical interaction method for 3D shape modelling. In this report, we present a study on user gestures and speech interaction for shape modification. With this experiment, we aim to study how users model and manipulate three-dimensional objects in a virtual reality environment through gestures and speech without using any additional device, i.e. no pointer or controller. It will give us a detailed and accurate perception of how users can interact naturally with three-dimensional objects in a virtual reality environment.