I looked up ice block and was surprised to find that it's only (?) used in NZ and Australia.
3 Cup (48 tbs), chop (into small peices)
1⁄2 Cup (8 tbs)
1. In a blender place the watermelon pieces and pour water.
2. Blend until smooth.
3. Pour the watermelon juice into the guitar shaped ice blocks.
4. Place it in the freezer to chill for couple of hours.
5. Serve the Watermelon Guitar Ice Blocks chilled.