I would say the screwdriver is the least safe... But for some reason attractive to Beagles. We had a cable guy with a tool belt at our house once. Floppy kept trying to steal the screwdrivers from his belt, and even got one once... Silly dogs.
Silly Zelda! Jersey loved hammers when she was a puppy. We got her not long after we had moved into our apartment and I was still doing a lot of picture hanging. Every time the hammer came out she'd try to steal it. A few times she'd succeeded and watching a four month old Beagle puppy drag a big hammer around was just hilarious.
You have to wonder sometimes why they steal what they steal. Are they looking for attention? Does the object taste good or smell like a person? I love the mischief in a beagle, and Zelda has it in spades.