You will need a whole selection of sweeties to decorate your daleks, I recommend liquorice laces or catherine wheels, red gummies, chocolate fingers and silver balls.
Place two cupcakes on top of each other to get the height of the dalek, you could use a cup to bake your cupcakes in and then you will get the shape.
Cover with roll icing, you can dye the icing grey with black food colouring.
Place the liquorice laces around the body of the dalek to make the patterns of it's armour.
Use two gummies for the eyes, chocolate fingers for it's "arms" and "nose" and silver balls for the bumpy bits on it's armour.