Here are some silhouettes I've drawn on Photoshop for my gingerbread house. I've decided that I'd like the house to be in two parts: the house-shaped section, which will be made of various types of crumbling/melting sweets and candy, and also a part at the back, which is essentially a crude, metallic chimney where the old lady burned all the bodies. This idea came to me whilst drawing, and on some level I was reminded of the old Dexter's Laboratory cartoon where Dexter and his rival Mandark's houses had comically-sized sci-fi laboratories stuck in their back gardens, even though they were meant to be secretive.
Of course I do need to keep in mind my skill level, and my structures won't be as complex in geometry-form as they are in my drawings. In the end the concept art will be to reflect the overall atmosphere I would like to create, and I'll have to express this to the best of my current ability without expecting too much. I'm planning on making a very rough 3D draft of the house to get an idea of how I'd go about modelling.