Here are some designs I’ve made with my Super Spirograph and various felt tip pens as I’ve described here.
As you can see, there are lots more colors available these days, compared to the old days when the set came with four ballpoint pens in red, green, blue and black. The pens would sometimes tear the paper as you drew a repetitive design with the pressure necessary to make a line. You don’t have to press so hard with felt pens, so the results are much nicer.
Modern felt pens come in various shades of the same color, such as light, medium and dark blue, which can add subtlety to your designs.
I find the gel pens, such as the metallic copper in these designs, more difficult as they dry slower, so they smudge more easily. Going slowly helps.