I like your Question, The problem is how to paint them, This is my out line.
Acrylic Paint Procedures - Rough Outline
1. Spray Plastic walls with Testers Dull Coat.
or Krylon Crystal Clear instead of Testers Dull Coat as it is much cheaper
2. If a brick building rub in a Acrylic Paint - Make a red brick color from Burnt Sienna & White or a red shade.
3. Rub in a Acrylic Mortar color with rag or cotton ball.
4. Paint doors and window trim with a fine brush.
5. Use a black chalk for a weathering wash or india ink.
6. Spray again with Test Dull Coat or Spray Lacquer.
Note: Acrylic Paint take longer to dry. but mixing of colors
work great on a card board pallet.
Weathering is the key to solve all problems