Silhouette portraits were made by putting the subject between a bright light and a sheet of white drawing paper. The resulting shadow was traced on the drawing paper and then cut out. These are often referred to as hollow-cut drawings.
The invention of a machine called the physiognotrace allowed tracing and cutting to be done in one fell swoop. What this means is that the silhouettes could be made faster, and even cheaper.
But this doesn't mean that all of the artists jobs were completely lost. There were experienced artists that could do full-length figures, scenes, ships, or even trains completely freehand.
Good hollow-cut early examples are hard to find, and can be quite pricey. The ones that feature a rare scene (like one of the full-length figures) can be pricey as well.
There are a couple of examples of silhouettes in my Etsy shop, which can be seen here.
What kins of silhouettes have you seen?