While still developing, I made a few renders to get a better Idea of the look of things. The cannon part is certainly the most difficult to model due to the inner transform mechanics. The first render below shows the different parts, while the second shows the different possible weapon forms. 

The 3rd phase is a separable particle cannon that clips on to the waist. The revolvers slide in and the two sides combine together, unfold and become the cannon itself. This phase is taking the longest to achieve, but I think the result will be impressive.

The next phase of the Revolver clips on the back when not in use. The next phase is considerably larger.

I had an epiphany recently in the shower (pretty much the location of most of my inspiration) and I thought about a 3 staged fictional weapon that started with the initial revolver that combines with other parts to become larger fictional weapons. Using the experience from the Laser Focusing Rig, I was able to get a very detailed start to it. 

I've been teaching myself how to use the animation software Poser and this dis-assembly render demonstrates my progress.