Fun with Fosshape – Making a Mad Hatter Hat



This project got started when my husband and I signed up for an Easter-themed race. Since I knew there would be lots of bunny costumes, I decided to go with Mad Hatter and White Rabbit outfits. I looked through all the available Mad Hatter hats, and they just weren’t mad enough for me, I wanted something really crazy. Since I had recently ordered some Fosshape to experiment with, I figured this was a great time to try it out.

In an earlier post I described how to use Wonderflex, a thermoplastic material that when heated, can be molded into lightweight shapes. Fosshape is also a thermoplastic material, but is more fabric-like than Wonderflex. At first look, Fosshape appears to be a thick white felt. But it is actually made up of polyester fibers that melt at about 200 degrees. It comes in two weights, the regular Fosshape 300 and Fosshape 600, which is twice as thick. It is sold by the yard in a 45″ width. The Wonderflex World website has a good FAQ on Fosshape.


I started by making a cardboard pattern that would also function as a form for my hat. Fosshape shrinks when it is heated, so you need to control the shrink if you are concerned with the size of the finished piece. Professional hat makers have wood head forms, but the closest I could come was my lovely mannequin. Her head is smaller than mine, so I put a ring of cardboard around her head to get it to my size.


Next I cut the cardboard open so I could use it for a pattern to cut out my Fosshape. I added about an inch and a half around the pattern to allow for a small seam allowance and shrinkage.


I sewed the back seam and then sewed the top of the hat on. Fosshape is easy to sew, even the heavier 600 weight that I was using.


Now I was ready to shrink and stiffen the hat. I duct taped my pattern back together and covered it with Press and Seal film to protect my mannequin.


Next I put the hat over the form and started to steam it. I tried both a household steamer and a steam iron, the iron worked better for me. You can also use a heat gun or a hair dryer. The trick is to heat the material without overheating it. You can melt a hole right through the material if you are not careful. The website has a good series of video tutorials on how to work with Fosshape: Part One, Part Two, Part Three.


I steamed the hat until it had stiffened and shrunk up to be snug against my form. When I was happy with the hat, I was ready to work on the brim. Again, hat makers have wood forms for brims, but I made mine from Styrofoam. I made a paper pattern, transferred that to a piece of Styrofoam, and then cut and shaped the foam into a brim shape.


Once I had the form, I cut out a piece of Fosshape and attached it to the form with pins. I put elastic around the top of the brim to snug it up to the form. I cut out the center of the brim, leaving material in the center to attach the brim to the hat. Then I started heating the Fosshape. I was more aggressive with the heat on the brim, since I wanted it to be firmer than the hat. I ended up pressing the iron directly on the Fosshape to get the stiffness I wanted.


When the brim was stiff, I took it off the form and cut off the excess to make a smooth rim. Then I hand-sewed the brim to the hat. I knew the stitching didn’t have to be pretty since it would be covered with the hat band. I was now ready for painting and finishing. Fosshape can be dyed, painted, or covered with fabric. I opted for spray paint. I printed the price tag, “In this style 10/6” (10 pence, 6 shillings) on heavy paper. I made a hat band from fabric that matched my outfit.


To make the hat as mad as possible, I decided to add tea cups and a dormouse. I made the tea cups out of Wonderflex and decorated them with paint and stickers. I found a mouse finger puppet that was just the right size to peek out the top. After trying on the hat, I decided to add some crazy white hair. I cut apart a white “mad Scientist” wig and sewed on just a fringe of hair. I didn’t want the hair too close to my face where it could get in my eyes and mouth.


Because the hat was sized specifically for my head, it stayed on snugly when I ran. The one thing I would change is to add a sweatband to the inside of the hat. It was fine for the 5K we were doing, but for a longer race I would want extra cushioning. I got lots of nice comments, including a couple people who said they used the hat as a “marker” to keep their pace. I had made a running skirt with attached shorts, a sleeveless tailcoat, and a bow tie to complete my outfit. My husband as usual was a good sport and looked great as the White Rabbit. I made his vest and bow tie and found a giant plastic pocket watch that made his outfit. I bought his hat, a black baseball cap with attached rabbit ears.

I’m already planning my next experiment with Fosshape. Like Wonderflex, it’s material you just have to play with to discover all the possibilities. I hope you will try your own experiments and make something really silly!