Make the mortar: beat the powdered sugar, meringue powder and 3 tablespoons of warm water for 4 to 5 minutes until thick and glossy. It should hold a stiff peak; add water a few drops at a time if it is too thick to pipe.

Spoon the icing into a zip-top bag, snip a small corner, and cover any extra icing with a damp towel.

For the roof triangles, an adult gently saws one graham cracker sheet in half diagonally with a serrated knife. Expect a few breaks; spares are part of engineering.

Pipe a thick line of icing on the tray for each wall, stand the walls in it, and pipe along every inside corner. Hold for 30 seconds, then let the walls set for 10 minutes before adding the roof.

Add the roof panels with icing along the top edges. Add pretzel beams or bracing where your design needs them.

Decorate with cereal tiles, dried cranberries and coconut snow. Let the house dry for at least 30 minutes before the earthquake test.