Thanks for the help, guys! Here's what I finally did:
1) I used a Dremel to cut the rear ends of the resin pieces flat, one slightly longer than the other.
2) Using the sander bit, I edged the piece, in order to make a slightly smaller diameter on the rear of the pieces.
3) I glued the barrels BACKWARDS into the brace, where barrel tips now rest against the brace.
4) I glued the Radio Shack connector pieces to the onto the sanded back ends of the barrel pieces (now the front).
Tonight, I'm going to paint the assembly gunmetal and silver and let dry. I'm also going to paint the inside of the front housing, so I won't have to paint around the barrels later.
After these parts dry, I'm going to JB-Weld the assembly, using the 'B' version above. So far, it looks pretty good.