Oldest tool in my toolbox? Probably the metal file from the set of tools I got when I joined the Revell Master Modeler Club as a kid. That was around '75. I think I still have some of the plastic pieces around somewhere; they were in a soft, red plastic. But haven't used them in years.
The plastic putty spatula was good, but the tweezers and the clamps weren't really that good.
The tweezers were too thick in cross-section, even at the tip, to make for a useful tweezers; hard to pick up and hold pieces.
The clamps were shaped sort of like an "A" with an open top. The crossbar provided the spring to keep the tips together, but again, the soft plastic meant that they were too weak to clamp anything.
Next oldest would be an X-Acto product, too. A #35 razor saw, with the red plastic handle and Nr 2 blades. I got that a couple years later, when I was 15. I was just learning to reposition figures, thanks to Shep Paine, and I had to get a razor saw. And the knife gave me a scar on a fingertip, that I have to this day. Learned to be more careful when working with hobby knives.
Got some old paints, too. Oldest is a bottle of Testor's gloss copper, in the little square bottle, which I've had since 1980? Still good. And a couple jars of Pactra's acrylic enamels, gloss colors, that are about as old, and still good.