Bob Brokaw began with a Power Point presentation covering many of the popular shop built vacuum press devices.  Vacuum pump devices are frequently used with vacuum bags to apply up to 1800 pounds per square foot of pressure to a piece inside of a vacuum bag.  This is commonly used when gluing up an irregularly shaped piece, gluing veneer to a substrate, or flattening a wavy piece of veneer.  The most common vacuum generators for a home shop are an electric vacuum pump or a venturi attached to a compressor.  Bob covered how to add pneumatic and electric controls to make either vacuum source cycle as needed in lieu of continuously running.  He ended by showing pictures of a number of different shop built pumps and demo'ed his own vacuum system that he uses for veneering.  Much of the material was derived from joewoodworker.com and veneersuppliies.com websites