Nah - just have the kit builders supply their own barrels. Just use a standard PVC size so that it can replicated. No sense moulding something that's easier to get off the shelf. That will cut down on the moulding (and shipping) grief and let you offer just the specialty components in the kit. If you decide to move forward and get stuck looking for a moulding partner, I'd be happy to help - just hit me up via PM if you're interested. I'm sure we could work something out...
Besides - someone still needs a Hammer!