Spread 3 cups of watermelon out on a baking sheet and freeze for at least 2 hours, until completely frozen through.
Add 1 cup fresh watermelon and lime juice to a blender and blend until smooth. Add the frozen watermelon and honey and blend again, then add in the tequila.
Pour the salt onto a small plate, then cut a small slit in a lime wedge and run it along the edge of your margarita glass. Dip the glass in the salt, then pour the margarita in the glass and enjoy! Keep any remaining margarita in the freezer until you are ready to drink it.