I really like this idea of having the kiddos set up their salt trays with their choice of colored paper--but definitely use the index finger for drawing & writing! Varying the material (corn meal, flour, grits, and even using pudding) helps reinforce prewriting shapes and letter formation.
Handwriting fun! Teach cursive writing strokes with watercolour paint
Sweet Tea Classroom: Integrate Fun: Cursive Writing and a Cat's Cradle
How to Teach Your Child to Write Their Name Using a Salt Sensory Tray
Sweet Tea Classroom: Integrate Fun: Cursive Writing and Art
Handwriting Without Tears: Cursive Handwriting
Ecriture par familles de lettres (selon Danielle Dumont)