I guess I don't quite understand the mechanism of these. Why can't you just stick an appropriately sized thing in the hole, like maybe an Allen wrench. what am I missing?
You're in luck. A few years ago I deconstructed one of these locks to try and make my own key. Ultimately that was a failed endeavour. I did save the parts so you can see how these things work. In photo #1 you can see the deconstrucuted lock. There is normally a spring but I couldn't find it. Photo #2 is a close up of the end of the plunger. Contrary to popular belief not all of these locks are made of hardened material. I cut this apart with a hacksaw.
This is how it works:
The tip of the plunger piece under spring tension forces the ball bearings outward so that the lock cannot be removed.
The tool is inserted and grabs on the end of the plunger (notice the point on the plunger and the hole in the end of the tool).
When you insert the tool it expands and grips on the inner edge of the plunger.
Then the tool is folded the plunger is pulled back, that allow the thin tip of the plunger to release the ball bearings but still keeps them in place.
