I don't like the idea of plastic to hold tools. Plastic is famous for
trapping moisture. Rust will not be far behind.

I don't like the idea of plastic either - in addition to potential
moisture issues, I can picture it tearing quite easily, especially if
used with any pointy or sharp or heavy tools. If you do go with
plastic, I'd use a fabric or mesh backing for the pockets, and see if
you can figure out some way of reinforcing the attachment points and
bottoms of pockets. Who knows - it could work well - let us know. If
you want an inexpensive, temporary solution of this type to try, you
could look for one of the "grandma's closet door shoe-pocket hangers",
something like this: http://www.dormbuys.com/index.php?
action=imageview&type=item&id=743
We use one of these organizers for little household stuff like shoe
polish, flashlight batteries, sunscreen, and other stuff that's not
used often but is nice to keep accessible.
As far as shop storage, my frequently-changing hand tool storage
system currently consists of the following:
Pegboard hooks for pliers, wrenches, squares, drill, earmuffs,
glasses, etc.
Pegboard hoops for screwdrivers
Magnetic strip for chisels
Home-made magnetic strip with rare earth magnets in a strip of poplar
for hand saws (this way the teeth aren't touching metal)
Small shelves for hand planes (the nicer ones are kept in "plane
socks")
Various other shelves, toolbox drawers, hooks, and screws in the
ceiling hold a variety of other tools.
Hope this helps,
Andy