Abstract: In this paper, we present a sketch-based technique for specifying transformations for general models by means of a single stroke, offering a more streamlined form of user interaction. The shape of the stroke is interpreted to allow composition of translation, rotation and scaling. We extract two main directions from the input stroke using Principle Component Analysis and use them to obtain an appropriate transformation for the model. Our method helps to have a more natural and faster way of assembling 3D structures. It is general and does not depend on specific knowledge about the type of models. As such, it can fit in the majority of graphics systems or modelling techniques.