This has become my favorite hat! I had a torn emergency blanket and wanted to find a use for it. Combining it with fleece it is an excessively warm hat. However the greatest benefit I have gained from it is its white noise effect. With the constant crinkle of the mylar I no longer need to run a fan for the white noise in order to sleep soundly. I do still wear ear plugs to sleep as well. This has been a huge help in my battle against insomnia and strange dreams caused by outside noises. My son also tells me that as a tin foil hat it protects against electromagnetic imaging of your brain, mass hypnosis, and memory implants but I will not substantiate those claims here.
With a rectangular scrap piece of fleece fold it in half to be the height of the hat which includes the desired pom pom at the top. The other measure is the length and should be at least an inch greater than the circumference of your head. With the mylar sandwiched inside the fleece it will not have the stretch you are used to. I often pull mine over my eyes to take a nap and my favored finished hat has 2 inches of extra length for the circumference. The mylar needs to have the full length of the fleece going around your head but does not necessarily need to have the same height.
Folding it in half so that the mylar is on the outside wrapped around the fleece. Its folded so all the raw edges of the circumference measured edge will meet. This creates a long tube with the mylar on the outside. If your machine is cutting your mylar consider lengthening your stitch or simply glue the layers instead of sewing. If you want a hat that looks like a mowhawk/mane you can skip this step but your circumference measure will need many more inches added onto it.
Turn your hat right side out flipping half of the fleece tube to be the outside and half to be the inside. The mylar should now be inside with two layers touching sandwiched between the fleece. Matching raw edges of the ends of the tube begin making cuts about an inch apart creating your tassels with the length of the cut matching your precalculated length for the pom pom top. The other end of the tube is now the hat brim. If doing the mowhawk version your circumference edge is still raw and should be cut into tassels as well coming up in a curve to the top of your head but you should still have the same finished brim after folding it correctly before you make any cuts.
Pinching the top of the hat tie around the top with a scrap of fleece. The Mohawk hat was created by keeping it flat and tying the tassels to each other. Don't miss catching the inside layers. The mylar is fragile and can tear so tying knots around the mylar tassels and not pulling them as part of the knot itself is easier.