Thanks Guy's. I shipped the CARB, amongst other replica weapons, to Soaring Hammer to be casted. You can view the intrerest thread in the Junkyard.
The Carb was mostly made out of PVC expanded foam board, and I used posterboard to do some of the overlays. I used liberal amounts of bondo and epoxie sculpt to get all of the round shapes. I started on this back in February, and I finished it a couple of weeks ago. Bear in mind I had about six other projects going on at the same time. But I think overall time to build this is about 2 months.
Thanks for looking at my stuff and feel free to comment.
MOD EDIT: Junkyard link removed.