it took me a couple of goes for it to look right as when i got bits wrong the colours ruined the white fimo. not to difficult though. make a big hole for the necklace chain, the chain i wanted to use didnt fit so i had to use something else instead. enjoy :)
flatten two balls of white and red fimo. spread the red one out more so it is thinner.
flatten one side of the red circle and put it on one half of the white circle. i cant really describe how it should look so look at the picture
tuck the extra pieces from the red circle around the back and smooth them down.
now roll out a long, thin, black sausage shape and two much smaller balls - one slightly bigger white one and one grey
flatten the grey and white balls and stick them on each other. then use the black sausage shape to line the large white circle.
use some more black sausage shape to cover the line between red and white and stick the smaller circles on top. with a pin put a hole through the top, cook the fimo and put a necklace chain through the hole.