Metal toothpaste tubes like those that Tom's of Maine toothpaste comes in. Cut them open and clean out the remnants, and you have heavy metal foil that is easy to shape (but stiff enoough to hold its shape) that is great for panels, doors, and clothing on figures. And it's already primed and ready to paint.
The metal over the ends of wine bottles (if you drink the expensive stuff) is also good for this.
Drafting pencil sharpener for sharpening toothpicks or similar items.
Those contact lens containers, the plastic ampules type, make great mixing containers for epoxy, and can sometimes be reused.
Contact lens solution plastic bottles: peel the label, rinse, and you have a handy, airtight, container for most water compatible solvents, mineral spirits, (but not lacquer thinner) that also makes it easy to dispense.
Cartridge brass: If you are or know someone who is a shooter, ask them for any brass cartridge cases they don't want: instant tubing, rings, and small brass wheel-like objects. Be sure to wash them in a high phosphate detergent before you cut them up. This is to remove lead compounds from either the (now long gone) bullet or the lead styphnate primer. For your sake, don't mess with loaded ammunition.
Speakiing of tubing: aluminum arrows come in a a wealth of sizes. When one gets too bent or beat up to refurbish, I keep it for tubing. You can also get scrap from an archery supply shop if there is one near you. These are usually short, from 1 to 6 inches long.