In Germany and Vietnam we had the opportunity to "play" with explosives. DUring team training in Germany we went to the range which had various targets such as armored vehicles, rail road rails, I-beams and field safes. A lot of teams went for the big booms but we worked on smaller charges such as punching small holes in safes. The trick to "blowing" a safe without destroying the contents is to be familiar with the locking mechanism. If you know where it is and how it is configured, you can open a safe with a relatively small charge.
In vietnam we had a lot of out of date 60 mm mortars that needed to be disposed of. I started experimenting and got to where I could blow or crack off the fuse without detonating the round. I made shaped charges just large enough to hold a cap. I started out with a ball od C-4 about the size of a golf ball and molded it into a cone and put a cap in the top.
I know that there are pastes and powders available but I think I may have fashioned some of the tiniest shaped charges that worked.
