I just this morning finished gluing up the main carcase for a dresser and discovered a great material for gluing cauls.  I had some leftover cork flooring from my wife's study and cut it into thin strips on the bandsaw.  The material is cork on two sides with a layer of rigid but somewhat flexible plastic in between and comes in pieces 36" x 12".   Since it is flexible it follows the contours of the curved legs perfectly.  Spreads clamping forces quite well. No muss no fuss.