QUESTION: 
What metals or materials are used to make up the MGS?

ANSWER from Charles Whetsel on February 24, 1997:
The majority of the MGS spacecraft structure is made from what aerospace
engineers refer to as "composite materials."  These are similar to
fiberglass, but instead of using glass fibers in glue, we use carbon fibers
in epoxy.  This allows us to make the box structure of the spacecraft both
stronger and lighter than if it was made from aluminum, which is what
spacecraft are traditionally made of.  Although the main structure is made
from this plastic-like composite, there are still several electronic and
propulsion components that have to be made of metal (aluminum or
stainless-steel) in order to function properly.