There is a recipe to turn the actual crystals into a cube of refined metal, I forget if it has a blueprint or not... but I believe it is craftable with what you have on the table already, I think it is only the welding torch and 4 crystals... maybe you need to wear the welding mask? You will need many more crystals regardless unfortunately. While talking about crystals, having lots of radiation sources around also seems to cause serious fps issues so make sure they are stored in a crate or something when not in use.
I hear rumor that there is a unique interaction sleeping in the cave so perhaps bring a second backpack with a sleeping bag for when you get tired, I am curious if this is true but I don't have the time to test it myself.