Felt hats come in many varieties and size, but a hat that's too big needs help. There are a few methods that will make the inside of the hat smaller. If the inside of the hat has a grosgrain ribbon band, this band can be altered to ensure the hat will fit. You can shrink the ribbon to make the hat tighter or sew another ribbon onto the existing one to create a tighter fit. If the hat is a head-hugging type hat, such as a felt ski cap, you can use thread elastic, or you can add a lining.

Wet a clean sponge thoroughly and squeeze some of the water out. Wipe the sponge along the grosgrain ribbon that is on the inside of the felt hat, or if there is no ribbon, wet the inside of the hat directly.

Thoroughly saturate the ribbon, or a 2-inch wide band inside a hat without a ribbon, then allow the hat to dry overnight.

Try the hat on. If it is still too large, wet the hat again, and place the hat near a heat source, such as an fire or heater. Another alternative would be to use a blow-dryer set to high heat.

Measure the ribbon that is inside the felt halt with a measuring tape. Add 1 inch to the measurement and cut a piece of grosgrain ribbon to that length.

Sew the grosgrain ribbon to the other ribbon that is inside the hat using a needle and thread in a matching color. Overlap the ends by 1/2 and sew the ends together

Try the hat on. If it is still too big, sew another layer of grosgrain ribbon to the new one. If it is still too big then sew another ribbon to the previous ribbon to make the hat tighter.

Measure the circumference of your head, where the hat is going to sit. Cut a piece of thread elastic, using that measurement plus 2 inches.

Sew the thread elastic inside the hat, along the part that will be sitting on your head, puckering the felt fabric slightly as you're sewing. If the hat has a lining, sew it to the lining. If the hat is a single piece of felt, sew it to the felt, using very small stitches, just grabbing the inside of the felt so the elastic won't be visible from the outside.

Cut the thread and tie a knot when you have reached 2 inches from the needle.

Measure the circumference of your head, where the hat is going to sit. Cut a 1-inch wide band of polar fleece, adding 2 inches to the measurement.

Fold the band of polar fleece in half and sew a straight stitch across the end, 1 inch from the end. Cut off 1/2 inch of fleece.

Sew the polar fleece to the inside of the hat, using a thread that matches the hat color. Pinch the fabric slightly to form small puckers in a few places to make the hat fit the polar fleece.