EXCELENT idea Femurat! I know just the things you mean - Some of the (older?) lever arch files have them for holding the pages in place as the file is moved. I've not seen one with those spring wires in for some time, but then I've not been looking either...
From what I rememner of them, the ones I had were VERY high quality spring wire and remarkably strong for their thiness. If you can bend them to suit, without loosing that temper, they might well be very good indeed.
For the bolt-thrower wire, I always used an asymetric "Z" shape. Actually, that's not exactly right on reconsideration, since the angles were 90 degrees, not the 70 degrees or so for a "Z". Sorry, being a pedantic here, but I'm sure you know what I mean - I just can't type the shape in ASCII art, since on pressing "submit" all the formatting is lost and it comes out a jumble mess.
I always start with the shortest part of the shape, the bit that fits in the lock and actually throws the bolt. You take this length from a key for the lock. Normally you only need a a simple "L" shape on the end, but if the key has the relatively unusual side-wards on it (cuts in the side and not just the end of the key), then you need a sort of cascaded 2 L's to get past them. Better to make them a bit too long as they can be cut down
The next part is the shaft. This needs to be long enough to get out of the lock, out of the thickness of the door and allow you enough room for you knuckes against the door. Personally I usually go for 2" to 4", unless it is for something really unusual. With these thin wires, probably best to go for something nearer to 2".
Whatever is left you make the handle from! With these shortish wires, you might not have a lot left and will need to make a handle for them. The smaller and lighter the better generally. A 3" to 4" length of 1/4" wooden dowel might be good?
With wire this fine, there is just a slight possiblily that they will poke between the levers in the lock and tend to become fast. If this happens, a small piece of aluminium about 1mm thick and perhaps 10mm long can be folded in half over the wire and pressed onto it. It can then be filed down into just a bit thinner than the thickness of the levers.
Remember that the most strength is needed for throwing the bolt, so if the wire proves too thin, then keep the bicycle spoke for the bolt-thrower and use the lever arch spring wire for the lever lifter "pick". Hopefully it should give you enough room for them to still work really well. I hope so, you are doing a good job
