I found a pretty crochet scrunchie pattern on youtube. Link here. MJ's Off The Hook Designs. I used a 4.0 mm bamboo hook and the same brand of yarn used in the tutorial. The yarn is a cotton/acrylic blend, fingering weight.
I made two of these. One for dear daughter and one for me. Each scrunchie took me about 4 hours to finish. It was a fun pattern to crochet and the instructions were very easy to follow.