The back of the pattern is flatter than the front. Measure the back with a ruler and determine the center of the Velostat sheet.
Place two strips of tape on the back side of the Velostat, one strip 1/2" to the left of the center and one strip 1/2" to the right of the center. Place about half of the strip on the Velostat.
Place the other half of each strip to the back of the hat.
Push the Velostat into the hat with your hand. Make sure the Velostat touches the inside top of the hat.
With the Velostat inside the hat, pull the hat and the Velostat over your head.
It may take several trys to do this successfully.
It works best if you put the hat and Velostat on the back of your head and pull it forward over your head.
Once the Velostat is as flush to the hat as possible, pull the hat and the Velostat off your head.
Trim the excess Velostat about 1/4" from the sides of the hat.
Pull the hat and the Velostat over your head again to check how it fits. When you remove the hat and Velostat, hold the Velostat to the hat with your hand so it doesn't slip out of the hat.
If you are sure that the Velostat is as close to the hat as possible, trim it up to the edge of the hat with a scissors. If you are not sure that you got the Velostat flush to the hat, remove the hat, push the Velostat back into the hat and put the hat over your head again for another try.
Secure the Velostat sheet to the hat with 4 or 5 strips of tape on the front and 3 or 4 additional strips on the back of the hat.
You can place one or two strips of tape on the sides of the hat to hold the Velostat, but final taping of the sides is done last.