Open an old VHS tape (the older the better) and look in the lid...
You can pull off a strip of spring stainless steel from it. It is used to keep the reels evenly balanced.
I've been making picks from them for years, they are too thin to last very long, but can be cut with a sharp pair of small scissors into micro picks for the locks with keyways that are so impossible for normal picks.
Incidentally, the stip is 0.020" thick, the slim picks from Southord are only slightly thicker (0.025"), but much more robust, due to the steel they are made from. Still, the old VCR tape springs come in useful occasionally...
Alternatively, look for a spiral-bound pad or book. The wire is a bit thin, but can be useful occasionally.
I've made picks for deadbolts and curtained locks from the wire used to make the shelves in an old fridge.
There's the usual welding rods and paperclips/bulldog clips of course.
Some CDs/DVDs can be split apart (they're two layers glued together) and some can be cut with scissors to make basic picks, like credit cards can be cut to make picks (or even a key - They only last a couple of turns usually, but if you trace a key onto an old credit card, and cut it out carefully enough, alarmingly it does work). Doesn't always work though, but often enough to make it fun and startling to see it actually work on your own front door.
A CD or DVD case can be cut in the same way, as long as it's not too brittle.
15mm (or 1/2") copper pipe offcuts can be cut open to make sheet metal tough enough for temporary keys.
I am currently experimenting with making flat keys from the fire safety plate that fitted under my old gas fire. It looks about right and seems hard enough. If it works, I can impression desk locks for life!