Concepts for Alien Guns:
I made the top image as a starting point. The client liked the style of # 3. Then I created the second image with a variety of sizes in that style. The client liked 1 & 7, so they were turned into practical props.
Props based on my designs:
I don't know who made these, but they are fantastic. We even had one around the shop to play with.
I painted the damage and some of the lighting on the robot. The robot was CG and modeled by another artist.
The plate already looks pretty great. I added a crater, and took a clean render of the CG robots and added damage and lighting.