3D paint systems opened the door to new texturing tools, directly operating on 3D objects. However, although time and effort was devoted to mesh parameterization, UV unwrapping is still known to be a tedious and time-consuming process in Computer Graphics production. We think that this is mainly due to the lack of well-adapted segmentation method. To make UV unwrapping easier, we propose a new system, based on three components : * A novel spectral segmentation method that proposes reasonable initial seams to the user; * Several tools to edit and constrain the seams. During editing, a parameterization is interactively updated, allowing for direct feedback. Our interactive constrained parameterization method is based on simple (yet original) modifications of the ABF++ method, that make it behave as an interactive constraint solver; * A method to map the two halves of symmetric objects to the same texels in UV space, thus halving texture memory requirements for symmetric objects.