I've changed background color to blue, and put a circle on it. I also changed the color of the inner part of the circle to white. Now I want to depict seams on it... how can I draw the seams?
I can accept that the seam is just the curved line - i.e. I don't need the dashed line or the "real" seam, which is a collection of small horizontal lines, since I don't like the idea of spending another 10 or even 20 hours just learning about how to draw a "real" seam. Here's the image that I intended to depict, though since I don't know how to depict it in a computational way, I just overlaid a circle on the original circle and erased the redundant part with an eraser by hand, and finally duplicated it and transposed the duplicated line. But since the hand-written curve is quite awful, I want to make the curve look more fluent.