First I wanna say thanks to all for answering my questions so quickly. This forum is very helpful. My question here is about 'merging to center' of points. My steps are: > combine polygons > then merge to center two or more selected points (usually just 2) till the parts are attached. In most cases the whole looks fine after merging two parts together... but occasionally i'll get like crease in the shape. not sure why. i circled it in the link below. any idea what i'm doing wrong? https://www.rossow-web.com/screen2.jpg