Additional design for manufacturability guidelines are available from the following links.
These general guidelines form a good starting point for a designer. Ultimately, an organization should develop company- or site-unique guidelines that consider it manufacturing process capabilities and the requirements of its products. An example of a company sheetmetal design guideline is available.
Another source for specific guidelines is from your outside supplier. Many suppliers have developed detailed guidelines based on their process capabilities and tooling.
DFM/A guidelines covering assembly, PCB fabrication and assembly, machining, injection molding, casting, stamping, and sheetmetal are available for license from DRM Associates.
A final source of guidelines is from industry organizations and books. For example, the Institute for Interconnecting and Packaging Electronic Circuits (IPC) publishes a number of guidelines such as: IPC-D-782A “Surface Mount Design Guides and Land Pattern Configurations”.