The flat Monocote will take paint better than the gloss film. Be sure its clean of oil and then paint ideally with oil based paint and it will last for a while. You can also cover the paint with polyurethane clear satin finish. Any weathering, light detail airbrushing, will need to be done slightly darker than usual because the clear coat will reduce the effect. You can also do some work first then clear then go back and accentuate whats been done for final effect.