They were used not only with wood veneer, but sometimes with bone, tortoise shell, even soft brass.
Below are some photos, limited to five per post. I'll post more in a few follow up posts. I've included two small flower images that I made. One of the closeup photos shows my wedding ring to give you an idea of the tiny size of the pieces - see the holly dots that were sawn out. I've also included a few images of pieces that were done in the 18th through the early 19th centuries (i.e., about the time of Napoleon), with the exception of a portrait done in 1930. They were used not only with wood veneer, but sometimes with bone, tortoise shell, even soft brass. Unbelievable detail, and done without the benefit of software to tell you what colors of wood to use for each part of the portrait, for example.