I enlarged the dimples on a rear fender to mount it on the front for my Ladies bike buildoff.
Bending them over a wooden dowel in a vise or on a bench may work for you. Use another piece of wood or something fairly soft to tap the metal outward on either side of the dimple, like you would use a punch.
You can use pliers but it will likely mar the surface. Pliers wrapped in tape might do the trick without damage.
Mark off the bend areas needed and work between the lines. Go slow and be prepared to test fit again and again.
--Rob