If you're familiar with the Korea virtual dating show, 'We Got Married', one of dating spots is a ring making cafe called Banji Market in Hongdae. To get there, walk towards the center of Hongdae, and turn into the alley with fruit on a stick in the corner, the street lined with most of the clothing stores. The ring cafe is located on the 3rd floor on the left side of this street, just look at the signs hanging off the sides of the buildings. The guy there doesn't know a lot of English, so it will be hard to communicate as a foreigner. He was very helpful and showed us the display, and explained which styles were more difficult to create. If you are studying abroad here, there is a student discount, so let him know you are a university student, and you will get 10,000 won off your total. The rings start at 40,000won (2.5 mm), 50,000won (3.8mm) and 60,000won (5mm), and the price is added for any additional designs (initials, engravings, birthstones). I opted for the 2.5mm silver flat band, with a birthstone and laser engraved initials. The flat band is the easiest, the rounded band is harder since it requires more shaping. He said he doesn't recommend it for beginners, but was really nice and helped my sister out with shaping hers.
Below is the booklet that shows the instructions for making the ring. Some of the steps he does for you. We mainly flattened the ends of the metal, then sized, smoothened, polished our ring band and then chose the design (initial fonts, and birth stone).
^The fonts for initials are on a separate booklet that he lets you choose from when you are done polishing.