If you like frozen margaritas, you'll be a fan of these ices, which up the ante with a thick slush.
Heat sugar, water, and juices in a small saucepan over medium heat until sugar dissolves, about 4 minutes. Let cool.
Stir together citrus syrup, tequila, and Cointreau in a pitcher. Divide among twelve 3-ounce paper cups. Freeze on a rimmed baking sheet for at least 5 hours. Garnish with lime wedges.
Ices can be frozen, covered with plastic wrap, for up to 2 weeks.