What I have used for is a bit yellow and red felt, some red beads, some fluff for stuffing and a golden thread.
First I have made a pattern in crown shape, a bottom and the middle piece (as in the picture). I have cut the crown shape twice to sew it together to make everything a little more stable.
Then I have added some red beads as "crown jewels". Then I had to swop the whole thing to sew the crown middle piece. After adding it, I have turned the whole crown again and stuffed it with some fluff. Then I have fixated to bottom and have sewn it to the rest. For all visible parts I have used the golden thread.
And that's how the crown looks, after finishing it: