Stock Shelf
The stock "shelf" is a collection of just about every possible material in every form that might ever come in handy in a project. For small work, the quantity on hand might be adequate, but often it's meant merely a guide for making design decisions. Then I order the actual amount necessary.
The original stock shelf was pretty cramped, and lots of things had to be stored elsewhere.
The revised version spreads things out better, but eventually this needs to be redone, as well.
Aluminum, steel, brass, PVC, etc.
All sorts of stuff: steel, aluminum, magnesium, titanium, cast iron, steel, nickel, exotic metals, kevlar, teflon, zinc, copper, Delrin, etc.
Graphite, which is wonderful for prototyping and mold-making (although messy), carbon fiber, and foam (also for prototyping).