In a small mixer bowl combine egg whites vinegar and salt
Beat with an electric mixer on medium speed until soft peaks form tips curl
Gradually add the 12 cup sugar 1 tablespoon at a time beating on high speed until very stiff peaks form tips stand straight and sugar is almost dissolved about 4 minutes
Use the back of a spoon to spread the meringue over the circles on the foil building the sides up
Bake in a 300 oven for 35 minutes
Turn off oven
Let meringue shells dry in oven with door closed for at least 1 hour