you can get mehendi tattoo stuff in little tubes just
made for this, so it draws on kind of like cake icing.
You can probably google it. I had it done at an
all-ethnic fest in OKC years ago, and I tell you there
is nothing like watching Indian women do this super
fast and super accurately. True mastery. If you are in
a fairly large city, you might find someone who could
visit your class and explain the cultural history of