Spread out some newspapers. Cut cloth 2" bigger than the grilles. Lay cloth down on the papers. Lay grille on cloth. Cut paper to fit inside the grille and cover the cloth so you don't get adhesive on that part of the cloth. Spray adhesive (I use 3M Super 77) on the back of the grille and on the cloth near the grille. Let it set up for several minutes. Start in the middle of the grilles, not the corners.....pull the cloth around the grille edge and stick it. Work your way toward the corners. Moderate stretching. Corners are tough part.....Need to pull the cloth out and then over the grille corners......you end up with several small folds of cloth at the corners.....press them down as tight as possible. Clean hands with lacquer thinner. Trim excess cloth with razor blade and maybe a straight edge.