I used an old camembert box, stiff tull (left overs from old flower bouquets), a shiny shopping bag, golden/beige ostrich feathers, ribbons and butterflies I made from Fimo and painted.
I prefer to use a glue gun, but all purpose glue should also do the trick.
Find a suitable gap between rim and base of the box. Lead a short piece of ribbon or fabric through the gap and sew into a loop. Do exactly the same on the opposite side. These loops will enable you to secure the mini hat on your head with either hair pins or a band/ribbon.
Cover in fabric of your choice. This is an old shiny shopping bag which I glued on a layer of fleece (...in this case an old ikea blanket).
This is roughly what your hat should look like.
This is where the fun part starts: The decor...
I glued pink satin ribbon all around to cover not neat areas :S
I then draped an old piece of tull (that once came with a bunch of flowers)and sewed it on.
I also glued a pink bow to the back.
Now it's just adding what you like and making it look beautiful. I for example added a butterfly (which I made of Fimo and then painted), some lace around the edge, artificial flowers, beads, feathers and sequins.
Et voila! A ready to wear party hat, that will make you stand out!