We did this with the youngest scouts. We didn't add sugar, but we did add the salt. We washed it though to seperate the buttermilk from the butter. The kids ate it on their dinner rolls at supper time. A craft I can get behind. The leader in charge of this activity (my wife) did it during a story time, talked first about the butter making, then read a story and the kids took turns shaking the jar and when they got tired they passed it to the next person.
Horizon 16" Classic, Kenmore gas grill, Lodge Dutch Ovens