The official DN plans include a design for a simple set of nesting "ice-claws":
I've made a number of sets roughly following that plan:
I made mine from 3/4" clear pine boards, and embedded a 16D common nail into the body. They nest nicely, stay together in one's pocket, and open up easily. I haven't had a chance to test them out "for real" (thankfully), but I've used them for a variety of ice-chipping jobs (ex. extracting something partially melted into the ice), and they seem strong enough.