"My doctor told me to quit throwing dinner parties for 4 unless there are 3 other people - [sigh]" - Gramps
This dried really quickly and nice and hard. It does require a "specialty" ingredient, but if you have it, it's really easy!
3 Tbs meringue powder
1 lb powdered sugar
4-6 Tbs water
Vanilla or Almond Flavoring (optional)
Whisk the meringue powder and powdered sugar together.
Slowly add water and flavoring while mixing with a hand mixer. Add enough water to make a smooth, thick frosting. The thicker, the faster it will dry. But it needs to be pipable so keep that in mind.
Divide into ziploc bags and cut the corner, or use actual piping bags.
About 2.5 Cups?
We divided this up into 6 piping bags and made basic graham cracker houses (and yard decorations). I think some people used all of their allotment, and others kept it more simple and had leftovers.