A sculpture sketch.
When I sketch, 2D or 3D, I don't do it to totally plan out a project. That would defeat the purpose of then making it (and make it really boring)! I sketch in order to collect moments that I find interesting, and to play with materials without the need for a finished project. Usually, if the sketches are "unfinished" they have enough of a freshness and an essence of the moment that it not only reminds me what I was seeing or thinking about, but it inspires me to make more work and to think more about it.