Seems like they have all the gold exterior items. You need to get over 1.1 million HHA points to unlock them all. Construction is free, if you choose to use it for your home.
1) Okay first get 150,000 points, Lyle will offer the gold house model.
2) Finish paying off your house - have all rooms and payoff all your mortgage - (Initially I did not realize I needed to do this first) If not, Lyle will not offer you the theme challenge.
3) Lyle will offer you the "Theme challenge". This means that you need your interior and exterior to be the same theme whichever one you pick (basement is not counted).
Tip:
*Start changing your exterior now to the theme that you are thinking of picking.
*You can fill up more than one room with the same furniture type and it will not be counted against you.
You will be offered the following once you reach certain points:
Golden roof - 300,000
Golden exterior - 500,000
Arched Golden door - 700,000
Golden fence - 900,000
Golden mailbox - 1,100,000.
I am doing the Antique theme and just waiting for one antique item to put in my house to get to 1,100,000 to get the golden mailbox.