Hi Alex,
Carvings on a 1/200 scale model are a relative concept. It is obvious that carving in wood is impossible. It is also nearly impossible to make carvings that really picture recognizable images. It's all fake. I use several materials to suggest the gingerbread carvings: 2-components stuff like Magic Sculpt or Miliput, or small threads of paper or gesso. The last can be made in little doses with a mixture of chalk, white glue and acrilic paint in the color you choose. Small blobs are added to the locations where they are needed, until sufficient volume is reached. Finally some 'sculpting' can be done with round and sharp bamboo sticks or something like that. It works both for relief work and for free standing statues. It's a matter of bluff. You don't have to create real carvings, they only have to look like them.
That's all I can say about it. I'm not particularly good in it, but it's a technique that can be learned.
By the way: how would you produce carvings with a 3D printer?