These are the sun-catchers we made at our glass class a few months back. The colors were twisted like this via putting the blob of colored glass in the oven and allowing it to melt and twist as it drips.
The one on the left was spun, to stretch it out, then pressed on a textured plate, lastly twisted at the bottom.
The one on the right was simply pressed in a circular mold.
© – Ilex Farrell