I had 4 stacks of aluminum coins hauled to the trade depot, threw together a bunch of macros, made a whole beard-load of trades, and then had 2000 individual aluminum coins. Cleared out my item-tossing chamber, and filled it up with coins. Sent in a steel-clad dwarf, and broke his hand. Oops. I looked through the combat logs, and found that one platinum bar had somehow sneaked in there. So I removed the bar, and tried with another steel-clad dwarf. Everything went smoothly.
I thought about it some more. A whole stack of 500 aluminum coins already weighs less than 1 Urist. So an individual aluminum coin must weigh less than 0.002 urists. That's hardly anything. So I sent in a militia dwarf, with bronze leggings, a mail shirt, helm, gauntlets, and high boots. He walked out unscathed as well. Looking through the combat logs more carefully, it seemed like most of the coins were being deflected by the cloak alone.
Curious as to just how little power a bunch of single aluminum coins have, I pulled the militia dwarf, drafted an unskilled, recently immigrated hauler, and sent him in in his regular clothes. I pulled the lever. It generated 20 pages of combat reports, but the idiot hauler was completely unscathed. I pulled it again. His stats were climbing steadily, but he was still uninjured. I pulled it again a dozen or so times for good measure. He still hadn't a scratch on him.
Gentle-dwarves, I give you what may be the perfect item for use in item-drop training, easily producable in huge quantities, gentle enough to but tickle your dwarves, while still fiendishly effective at maxing out their armor skill and attributes. I call it, "The Coinstar".
The hauler's protection:
The combat report:
His response:
His stats before one lever pull:
His stats after: