Johann Gottfried Schadow (1764-1840) was a Prussian sculptor of broadly neoclassical character; here are some pictures of the delightful images that he made of Luise and Friederike, two princesses of Mecklenburg-Strelitz who married two sons of the King of Prussia in the 1790's. Firstly his double portait of the pair in marble, dating from 1797. Sorry about the unappealing grey tones.
A terracotta bust of Friederike, 1794.
A marble bust of Luise from about the same time.
Luise as Queen of Prussia in 1798. She became an almost legendary figure in Germany as a result of her travails during the Napoleonic wars. She died at a young age in 1810. More about her here:
A very nice German site which has these large galleries of pictures:
Some details of the terracotta of Friederike. Such a lovely material.