A few more days of work and I created the base using ply wood and some sturdy cardboard. Then with a little spray paint (flat black) I got myself some nice looking base structures.
The part that you don’t see is the fact that the back of the gun opens using a wing nut on a large screw attached to the PVC.
Also, I had to use Bondo to make the foam paintable. Fyi, don’t try to spraypaint foam, it melts.