7.

Curve the strip slightly as shown in the photo. Dust it.

8.

Don't wait for the strip to dry out completely (you want to be able to adjust its shape to the curved side of the cake). Stick the doorstep to the cake.

9.

By now the door should be firm enough - try to peel it from the board. If it still feels stretchy, leave it for a bit longer to dry. If it is holding its shape place it on a piece of paper towel and dust it with brown dust. Move the brush from the edges inwards and along the plank lines.