Christian Alzmann was one of the veteran ILM concept artists working on Star Wars: The Force Awakens. Seen below are some of the early concepts he created, including the rolling droid/BB-8, stormtroopers and a sith villain/Jedi Killer. Be sure to check out more of his work featured in the art book, The Art of Star Wars: The Force Awakens.
Link: www.christianalzmann.com
All images © Lucasfilm, Ltd.