Collaborative systems are well established solutions for sharing work among people. In computer graphics these workflows are still not well established, compared to what is done for text writing or software development. Usually artists work alone and share their final models by sending files. In this paper we present a system for collaborative 3D digital sculpting. In our prototype, multiple artists concurrently sculpt a polygonal mesh on their local machines by changing its vertex properties, such as positions and material BRDFs. Our system shares the artists' edits automatically and seamlessly merges these edits even when they happen on the same region of the surface. We propose a merge algorithm that is fast-enough for seamless collaboration, respects users' edits as much as possible, can support any sculpting operation, and works for both geometry and appearance modifications. Since in sculpting artists alternatively perform fine adjustments and large scale modifications, our algorithm is based on a multiresolution edit representation that handles concurrent overlapping edits at different scales. We tested our algorithm by modeling meshes collaboratively in different sculpting sessions and found that our algorithm outperforms prior works on collaborative mesh editing in all cases.