Ominous, When you weld vertices you get three options; Use default tolerance Weld all selected vertices Use custom tolerance Now tolerance is the distance between vertices that you select that it welds together. If the tolerance is .1 and your vertices are farther apart than that, nothing would be welded. If they are less than that, they anything with .1 unit of a vertex would be welded together. The easiest way to deal with this is get your two halves as close together as possible, then select the central line of the model (aka the mirror points). Choose weld and then select custom tolerance. Now I usually use .1 in custom tolerance, but in the Carrara preferences area you can set the default to whatever distance you want. If your model is small, then you probably want a smaller value. If the weld doesn't completely work, then undo (Ctrl-Z) and weld again with a larger/smaller value. Keep an eye on the statistics in the sidebar. The selected vertices should drop to half the previous number after the weld. As for the sharpness, after the weld keep the same selected vertices and run the smooth command (Selection->Smooth edges->All). This should rid you of the creasing. Ken