Inlay is a process by which you make indentation in the surface of a pot and fill it with a different colour of clay. The filled clay does not have a clean line, so you fill in excess and then scrape it off, which leaves a clean line. At least that is what I do. Some people make a textured indentation and follow the same but my whole pleasure in inlay is from the clean sharp lines.
I have used the kolam, as an inspiration for its crisp lines, and also exploiting the cylinder as a shape which gives a good playing field for these lines.