They're made with felt and stitch up quickly. I experimented with different felts and prefer the wool blends that I found at Joann's. The acrylic felt by the bolt worked fine but I found a huge difference in the quality between the different bolts; some of it was pretty flimsy and looked fuzzy along the edges when I cut the shape out. I didn't use the craft felt sheets that you can find in craft stores since I don't think they would work well.
My three year old is modeling a Posy Hair Pretty that I made into a ponytail holder. I used 30% wool blend felt for this and love the way it turned out. I tried this ponytail holder on myself and it was really fun to wear!
Here is a view of the back:
You can turn Posy Hair Pretties into Hair Clips, too! This photo shows the three different options (full instructions are included with the Posy Hair Pretties design set as well as where to buy the clips.)