You're overlooking one problem. Jim said, or implied, that he needed to
schedule the paint booth by time and make sure it's not overallocated.
Material resources are consumables that are used up by the task - lumber,
bricks, fuel, video tape, etc. They affect costs but they do not affect the
schedule. In effect, Project considers materials to be infinite in supply
and instantaneously available whenever needed 24/7. They do not have a
calendar of available times nor do they have a maximum allocation that
cannot be exceeded. Equipment resources, on the other hand, are resources
that in fact do work just like people - bulldozers, cameras, airplanes - and
their availability affects the schedule, just like a person's will. You
only shoot a scene in a movie during a time when you have a camera available
but during that scene you can shoot as much film as will go through the
camera. So they must have a calendar of times when they are and are not
available (though it may be 24/7) and an indicator of how MUCH of the
resource (3 cameras = 300%) is available at any one time. I don't
understand why you seem to feel that the only work that should be included
in the project's metrics is that performed by human beings. The total
effort expended to dig a trench is the hours put in by the back-hoe operator
and the hours the back-hoe is in use and both efforts contribute to the
project's costs. Since work and duration are two entirely separate (though
inter-related) measures, summing the human hours and equipment hours doesn't
introduce any problems I can see, especially since with grouping (simply
enter something like "Equipment" in the resource group field) allows you to
break out the totals at will.