Make the Watermelon Juice Add the watermelon to the bowl of a high powered blender. Blend on high until the watermelon is liquified.Strain the juice through a fine mesh sieve into a bowl or glass cup measure. Discard the fiber. Make the Sugar Hollow Rub the inner rims of a coupe (stemmed cocktail glass) with lime peel. Discard the peel.Combine the gin, campari, lime juice, maple syrup, watermelon juice, ground cardamom and ice in a cocktail shaker.Cap and shake vigorously until the cocktail shaker is very cold to the touch (10-15 seconds).Add the watermelon rind to the glass.Strain the cocktail into the glass.Serve immediately. Enjoy!