How to build gingerbread house carton
Here's a tutorial you might find helpful Jay! https://www.instructables.com/id/EASIEST-MINI-GINGERBREAD-HOUSE/
Here's a tutorial for small milk carton gingerbread houses: https://www.simplykinder.com/milk-carton-gingerbread-houses-how-to/
here is the easiest way https://www.pinterest.com/pin/438256607488388377/
The easiest way is to use graham crackers, and attach them to the carton with royal icing. The royal icing is important. It's got eggs in it, so it sets up hard like glue. If you use canned frosting or other buttercream it won't hold together well.
I remember making these gingerbread houses when my kids were little. Attach graham crackers with icing. Jessica is right. Has to be royal icing. And then plenty of different candies to decorate with. So, Jay, here's the recipe for royal icing: 500 grams of sifted powdered sugar, a quarter-teaspoon of cream of tartar, 3 egg whites, and one teaspoon of your favorite flavor (I just use vanilla extract). You can also separate the icing in to different bowls for adding different food coloring, optional. The fun part of this is decorating it with candy.