Adding a curved brim to a top hat or any hat with a wide brim will give you the versatility to change it's shape again and again. An adjustable curved brim hat lets you alter your look to suit your mood. Curve the brim up, down or one side up the other down, making the brim of your hat curved and bendable gives you one hat with many different styles.
Open out one edge of the bias tape and fold the end over twice for a finished edge. Find the center back of the brim and starting there, pin the tape to the outer edge with the folded edge of the tape face up.
Pin the raw edge of the tape to the outer edge of the brim. Keep the edges even and pin the tape to the brim all the way around until you are at the center back again.
Overlap the ends of the tape and cut the extra tape off. Turn that end under twice and pin in place, edges even.
Machine stitch along the crease of the tape around the brim of the hat.
Turn the tape to the outside of the brim, press flat to the brim with your finger. Do not unfold the tape, you want to keep that finished edge.
Tape the ends of the wire together and lay the wire on the outer edge of the brim.
Encase the wire in the tape by folding it over the tape and slip-stitching the bias tape to the hat brim. Make your stitches small between the tape and brim just catching the fabric on the brim of the hat being sure not go through the brim.
If you can't find a bias tape colour that matches your top hat you could also use a wide ribbon.