Cut the watermelon in half using a serrated knife. Cut each half into semi-circle shaped slices about 2-inches thick. Cut away the green rind. Cut the red flesh into 2-inch cubes.
Add the watermelon cubes to the jug of a blender. Blitz until smooth then pour through a metal strainer set over a large bowl.
You will need 3/4 cup watermelon juice for these gummies. Reserve any excess watermelon juice for another use.
To make gummy candies:
In a small bowl, place 1/2 cup of watermelon juice. Sprinkle over the gelatin powder and set aside to bloom.
In a small pot, heat the remaining 1/4 cup of watermelon juice with the sugar over a low heat, stirring constantly, until the sugar has dissolved, and the juice is warm.
Remove from the heat and immediately add in the bloomed gelatin mixture. Stir until the gelatin has melted in completely. Add the lemon juice and tequila and stir.
Pour the mixture into silicone watermelon molds (these are commonly sold as ice cube molds online). Let set for 4-8 hours at room temperature to set. If leaving for longer than 8 hours, chill the gummies after they have set.
Once set, carefully pop the gummies out of the watermelon molds and set on a large plate or lined baking sheet.
Place the green candy melts in a small heatproof bowl set over a pan filled with 1-inch of water on a low heat on the stove. Stir occasionally, until the candies have melted, then remove from the heat. Repeat this with the dark chocolate chips in a separate bowl.
Pour the melted green candy melts into a disposable piping bag. Snip off the very tip to make a small opening.
Repeat this with the melted dark chocolate in a separate disposable piping bag.
Pipe the green candy melts onto the outer curved edge of each gummy candy to represent the rind. Pipe small ‘seeds’ onto each gummy candy using the dark chocolate. Leave until the chocolate and candy melt decorations have set then serve.