I carry a pair of tweezers in a pouch on my belt and when I'm out and about I do find them very useful on occasion.
I think the best bit of metal that, er, springs to mind to make tweezers very easily is that thin strip that you wind onto a little key when you open a can of corned beef. A length of that three or four inches long would probably make pretty good tweezers just cut, flattened and folded. Here's what I think I'd do if I lost my tweezers, didn't have a corned beef can handy, and absolutely had to make something to do the job.
1. Take a small stick, something like 8mm diameter, and bind one end so that it won't split.
2. Split the stick from the other end, down to the binding.
3. Run a bit of binding or something down into the split, to separate the split parts from each other a little at the end away from the binding. Now I have something a bit like a solid wooden clothes peg.
4. Find a bit of metal such as a barb from a barbed-wire fence, or a tin can, cut it to make two small jaw pieces, possibly shape them a bit (assuming I haven't lost my multi-tool as well as the tweezers).
5. Either press the jaw pieces into the two split ends of my bit of wood, or bind them to it. For stability, if pressed in they'd need to have sharp ends, if bound they'd either need to have a more or less flat surface or else be bent tightly somewhere near the binding.
6. Mess about bending the jaw pieces to get the tips to meet.
7. See if it works.
I've seen quite a few pairs of tweezers that have tips separate from the springy parts, e.g. on twin-pan balances for handling the very accurate weights, so having separate tips and forceps isn't a new idea.
All this would be near enough impossible for me (as would using a pair of tweezers to do anything fine like pulling out a thorn from my finger) if I didn't have my glasses and a magnifying glass. I always carry both, and spares.