Combine 1/2 c. sugar and cinnamon; set aside. Punch dough down, and divide in half. Turn one portion of dough out onto a lightly floured surface, and roll to a 28x10-inch rectangle. Spread half each of butter and cinnamon mixture on dough. Roll dough, jellyroll fashion, starting at long side. Gently place dough roll, seam side down, on a lightly greased baking sheet. Bring ends of dough together to form an oval ring, moistening and pinching the edges together to seal. Cover and let rise in a warm place, free from drafts, 20 minutes, or until doubled in bulk. Bake at 375 degrees for 20-25 minutes. Repeat procedure with remaining dough, butter and cinnamon mixture. Decorate each cake with bands of colored frostings, and sprinkle with colored sugars. ----