Cerrosafe should be strong enough though I have never tried it like that. I have used it making chamber casts in firearms. Depending on the application, there may be enough "sprue" left over to turn the casting out. Cerrosafe shrinks for a short period of time after cooling which should allow it to be easily removed/screwed out. Do not leave it in to long and follow the instructions as after a period of time it will expand. It is also reusable, just remelt it. Be careful using it in areas that are extremely sensitive due to heat getting the metal into other areas and not being able to get it out easily. I did something like that in a lever gun receiver.
