Create your character using a series of photos taken of the character model from all sides or a series of drawings from multiple angles. Mark an outline of your character using a marker on the sides and top of a foam block large enough for the character sculpture. Shape the foam by cutting away sections with a hobby knife or serrated kitchen knife to get a rough shape of the character. Shave away smaller portions of the foam using a wood rasp and sandpaper to provide details. You can also alter the shape of the foam by compressing sections with the pads of your fingers to the desired shape.
Hollow out the eye sockets and mouth of the head of your character with a hobby knife for the placement of manufactured eyes and false teeth if you desire a realistic look for your character. Sand the sides of the hollows smooth with fine-grit sandpaper.
Sand the rest of the foam character smooth with fine-grit sandpaper and then wipe the surface with a clean cloth to remove any sanding residue.
Mix the two-part resin in a plastic cup using a wooden stir stick according to the manufacturer's instructed mixing ratio. Brush the resin onto the character using a paintbrush in a thin layer. Allow the resin to dry slightly until it's tacky but no longer appears wet.
Place the fiberglass cloth over the resin, cutting the cloth into strips with scissors so that it fits smoothly over the character, with a slight 1/2-inch overlap where pieces meet. Brush a layer of resin over the cloth to fill in the pores and help adhere the cloth in place. Allow the resin to dry overnight.
Sand the overlapping edges of the fiberglass smooth with a fine-grit sandpaper, removing all signs of the overlapped lines.
Spray the character with a primer to prepare the surface for painting. Allow the primer to dry completely before painting the character with the colors of your choice.