You will need:
A head mannequin. I bought this one.
A heavy duty craft knife
An elastic band
White gloss spray paint
A glue gun
A long thin vase which fits inside the mannequin
1. First asses what you need to do with your mannequin. Everyone will be different (unless you bought the same as me!) and so you'll need to decide yourself but I judged that the whole thing needed to have the bottom lopped off.
2. Your mannequin will also need to be entirely hollow. Basically you need to have a continuous area between the head (where you're going to put the flowers in) and the body which you will place over a long thin vase. That way the flowers can get water.
3. Using a craft knife, hollow out the head and neck. The plastic used for this type of thing are usually very easy to cut.
4. If you need to cut down the body, stretch an elastic band around the body and then draw around the edge with a sharpie.
5. Saw using your hacksaw.
6. Roughly sand off the base of your vase.
7. Now time to work on the head (shudder). Draw your hairline onto the head, you will use this as a marker for the drilling.
8. Now drill yourself a tonne of holes. Make sure that the hole is large enough for the average stem.
9. Using a glue gun, attach the head onto the body.
10. Now time to paint! Make sure to remove any external pieces like false eyelashes first, as these won't paint well. I didn't need to sand beforehand, but if your plastic is very shiny it might be harder for the paint to adhere to. And you're done! After drying time, fill up your tall vase and place the head vase over the top and you're ready to create a flowery hairstyle!