There are lots of design tools out there that can be used to generate MEP or HVAC fabrication drawings, including spooling and integration with Vulcan or CAMduct. Some are FABmep, CADmep, ESTmep, and Sysque.

There is an interesting discussion going over on LinkedIn regarding Revit and duct fabrication. The overall message seems to be this: if you want to use Revit as an integral piece in your MEP fabrication process, you should probably be looking seriously at SysQue:

via Jim Reis on LinkedIn

Source video page:
TSI User Group 2014 Making the Switch CADmep to Revit with SysQue – YouTube

Video description

Customer Presentation: Making the Switch: Jumping from Fabrication CADmep to Revit with SysQue

Tom’s presentation will cover PCI Skanska’s implementation of SysQue, the transition from CADmep, the challenges and benefits of this progression, and its potential benefit to a large-scale and diversely located company such as Skanska USA.
After attending this session, attendees will be able to:
• Recognize the benefits of working in Revit
•See the big picture Revit setup: 

-Workshared project template
-Overview of shared parameters for a company 

 -Library creation of details and schedules
• Understand pipe systems setup for a company
• See what a contractor could expect from a Revit model
• Leverage the data in a Revit Model

Speaker: Tom Fuller

CADmep Object Enabler is a free downloadable collaboration utility that
enables ObjectDBX host applications (i.e. AutoCAD, AutoCAD LT, Volo-View
and Navis) to view the enhanced objects from CADmep.

Read more:

Autodesk Knowledge Network

The Autodesk Fabrication CADmep Object Enabler applies to both 32-bit and 64-bit Windows.

Autodesk Fabrication CADmep 2014 OE — Build 3.02.600 SP2b (exe – 270334Kb)

Autodesk Fabrication CADmep 2013 Object Enabler
– 246856Kb)