Repair Porous on Old Cars

having an old car is a hobby,this is my toyota starlet car made in 1985 or already 32 years old.
with age like that fair if the car has a lot of porous let alone we live in coastal area.
to overcome this I use fiberglass to repair porous on my car.


by using fiberglass I do not need to bring to the garage because it can make their own based on the instructions on youtube.
in terms of cost much cheaper and more durable to porous.