It is a technical challenge for several reasons: fire and paper are not best friends. The coloration has to come from a certain amount of the burn being forced into the paper or singing the top. The gunpowder itself would rather just burn up leaving very little mark on the paper, so a certain amount of compression is necessary.
Here are some working images:
and here is a video of the drawing process:
Here is the newest thing I am hassling with… a man with water-tower or windmill legs:
On the first phase of gunpowder burning (shown above) the paper was burnt into a black mess in one area… design solutions abound. Below is about 8 hours of masking and cutting before the first burning.
Here is the result of phase 2 :: the second burn to silhouette the figure and add some interest.
I also cut out the badly burned areas.