Step 1: Supplies
An old belt
Needle and thread
Larger needle than you will actually sew with, or small nail
Step 2: Measure, Cut & Glue
Use your first measurement as the length to cut your belt. Simply decide what section of your belt you would like to use, measure the length to match the ear to ear measurement you already took and cut. Set aside for a moment.
Now subtract your ear to ear measurement from your total head circumference. For example, my measurement was 23" around and 18" ear to ear, so 23-18= 5". This is the length you should cut your elastic.
Take about an inch of elastic and attach it to the back of the belt piece with craft glue. Press firmly for as long as it takes your glue to bond. I used quick drying glue (Krazy Glue did not work), but you may need to secure the elastic with something like a paperclip and come back to it if the glue you use takes longer. Once dry (or at least stable), repeat with the other side, connecting the ends of the belt piece with the elastic band. Be sure your belt and elastic make a continuous, untwisted circle.
Allow both ends to dry completely.
Step 3: Sew the Elastic
Secure the elastic to the belt by sewing through the holes as if you were sewing a button. Test strength of hold before you finish and tie off your thread. Repeat for the other side of the belt piece and test strength of elastic to be sure it is secure enough to be stretched around your head.
Step 4: Trim and Wear!
That's it! This will probably feel tighter going over your head than a store-bought headband, but it will also fit more securely and won't require so much fidgeting. I've been wearing this one for almost three hours now and have yet to require adjusting. Score one for oddly sized heads!