[JMay]

Ditto Chappyman66’s approach using automotive high build primer, then Halfords or Hycote rattle cans for top coat. Filament shells need more sanding than resin so I use 400-600 grit prior to the primer coat then 1200 grit afterwards before top coat. Revell Plasto filler works well on filament shells which I use on the join lines between segments (where I chop the back off to print vertically) and deep troughs.

   

Cheers
John