The upper piece has 20 gauge wire as part of the cording while the lower piece is just wrapped with thread. The base cording is actually three pieces of worsted weight yarn. If you would like to try this technique and see some great examples of how to use your custom cording, the folk at the Creative Textile and Quilting Arts site have a free on-line tutorial in this technique. You can access it here. This technique would be great for creating custom colored cording for purses, pillows, clothing or art quilts. When I used to do a lot of hand embroidery I would take my leftover threads at the end of a project and create cords and tassels with them. Now I have a use for leftover thread from sewing projects when I have over bought.
Try this out, you should be pleasantly surprised by the results.