Fillering Process

I used Polly Filler to hide the join lines and sanded it all back with sand paper and then gave it a few light coats of spray filler and sanded that back gently with some Wet & Dry Paper.
Unfortunately when I began to paint it turned out It wasn't as smooth as I had thought, so I had to sand it back and apply another layer of Polly Filler and then another layer of Spray Filler.