I made a mistake with my rudder which was red. I found a 160gm card in a stationers that was a perfect colour match, and the beauty was, the colour went right through the card so no edge colouring was required. I opened up the scan of the parts in MS Paint and removed all the colour within the black outlines. I then printed the parts onto the new red card. In future, If I build a downloadable model, I will purchase coloured card of the same or similar colour as the mono coloured parts and repeat the above process. This will not be as expensive as it sounds since I will not need to purchase expensive spray adhesive to laminate to card and I will not need to print in colour on my printer.