A $25 vise from Home Depot will crack all slabs open. You may need to do it length as well as width and make two tightenings, cover with paper towel to avoid flying shards, but I have never cut myself of damaged a coin.
There are some people that claim to use hammers. They can tell you about their experience after they get out of the emergency room.
Edited by Andrew99
10/16/2019 12:58 pm