Put the watermelon in a blender, blitz until smooth then pour into 6 popsicle moulds, filling each mould about three-quarters full. Tap them on a hard surface to remove any air, then place in the freezer for 1 hour.
Put the kiwis in a blender and blitz until smooth. Pour the kiwi purée into the popsicle moulds on top of the watermelon. Add a stick to each mould