when build designs unlock.

[briarwyn]

 When does the den building designs like cottage and eastern village unlock? When the forest guardian is brought back, or when the player's custom colony is set in place, in an area? And this question goes for all the designs that are sold by Ember, Delta, and Savannah. 

[Catsquid]

You can only buy the colony styles after you have made your own Custom Colony. If you've only finished the quest but not chosen to start the new colony yet, it won't happen.