um, i'll try and explain it, but feel free to ask more questions if i'm not clear
(i probably wont be)
the hat is made of matboard ( a thick sturcy card you get from picture framing shops, they use it to put coloured borders around the pictures) covered with whatever fabric you want.
1)i found the easiest way to do it was to find a tin can you like the size of and cut the matboard to the same dimensions, so you'll end up with a rectangle of card that will roll into the tube of tha hat, and a round top.
2) deide how wide you want the brim to be and cut a circle that size out of card, then cut a hole out of the middle the same size as the bottom of your chosen can. its a good idea to try fitting all the card peices together to make a hat shape before you go any further to make sure you dont want to make any adjustments.
3) cover all pieces with your chosen fabric. i do this by just folding a piece of fabric in half, placing the card in the middle and seing around the outline(i'm not a very good sewer yet
) but you can do it however you like. the edges on the rectangle and top circle dont have to be great because they'll be tucked inside when you sew it. remember to keep the hole cut out in the brim piece, so you have what looks like a flat, fabric covered ring, but leave about 5mm to 1cm of extra fabric around the inside edge, you'll need it later
4)curve the long ends of the rectangle together and sew to form a tube, i find it helps if you pin or even staple the ends together while you sew them, otherwise the card tries to spring out again.
5) push the top circle into the tube (i've found you get a nice finish if you push it up from the bottom of the tube, as it makes sure the fabric is taut(sp?). once it's sitting level with the top of the tube pin it(just push the pins through the outside of the card tube to they hold the circle in place), and sew the circle to the tube edge with small stitches all round the circumference.
6)push the brim ring onto the bottom of the tube so that bottom of the tube is level with the ring base. use the 5mm or 1 cm of extra fabric left around the inside of the ring to securely sew the brim to the base of the hat, it's sometimes a good idea to sew round it twice for strength.
7) add any decorations you need and a way to secure it to your head and your mini top hat is finished!
i hope that wasn't to long winded and hard to understand, i'll try and remember to take step by step pics next time i make one