Making a gingerbread house is a really fun holiday activity and they make cute decorations too. BUT, they can be a lot of work and a big mess.
An easy way to let kids make their own gingerbread house without a lot of expense or hassle is to use graham crackers. Of course you can't eat, but who really wants to eat something that has been sitting out as a decoration for days?!?
To make the gingerbread house, just use a single-serve milk carton. Use icing (from a can, or whip up a batch of buttercream frosting) as a paste to attach the crackers to the carton. Then the FUN part is to use any types of little candies, marshmallows or other treats you have handy to decorate, using more icing to make them stick.
If you want to make a larger house, you can use a full-size milk carton and cut off the bottom half to make it into an appropriate house shape and then cover with multiple graham crackers and decorate.