Fiberglassed the A-pillars yesterday for the tweeters.
I Cut the hole for the tweeter pods, glued the MDF rings to the A-pillars after aiming them.

Used toothpicks and glued them to the rings and A-pillar, so that they hold everything in place until the FG dries. You can also use wooden sticks or pencils for holding the structure in place.

Applied a stretchable cloth over it with the help of GMSA glue (elfy).

Applied a coat of resin over the cloth from outer and inner side.

After the resin was a dry, I applied a layer of glass mat + resin over it ( sorry, forgot to take the picture). FG work done here, the A-pillars are now sent to the painter for getting painted.