a 12-cup silicone bundt pan or gelatin mold; cocktail picks
For the yellow layer: Spray a 12-cup silicone bundt pan or gelatin mold with cooking spray; set aside.
Combine the lemon gelatin and hot water in a large bowl. Stir until the mixture is dissolved. Add the orange juice, tequila and 1/2 cup cold water. Pour the mixture into the prepared pan. Refrigerate until firm and the gelatin doesn't stick to your finger when touched, about 4 hours.
For the orange layer: Combine the orange gelatin and hot water in a large bowl. Stir until the mixture is dissolved. Add the tequila and 3/4 cup cold water. Pour the mixture into the pan over the first layer of set gelatin. Refrigerate until set, about 4 hours.
For the red layer: Combine the cherry gelatin and hot water in a large bowl. Stir until the mixture is dissolved. Add the tequila and 3/4 cup cold water. Pour the mixture into the pan over the second layer of set gelatin. Refrigerate until set, about 4 hours.
Run a small, thin knife around the edge of the set gelatin and turn it out onto a large flat serving platter. (Coax the gelatin out by gently pressing on the top and edges of the silicone mold.) Keep refrigerated until ready to serve, up to 4 hours.
For the garnish: Just before serving, garnish with orange wheels and maraschino cherries skewered on cocktail picks.