Yes you can use epoxy glue inside. You can use it anywhere.
Epoxy will do this .
calcium glue
You can use epoxy or super glue to glue stones together.
Epoxy.
An epoxy is best for this.
Use a good epoxy .
Epoxy is best for that.
Any kind of epoxy is best for this
Most people don't like them glued together, however it could be done with epoxy or possibly super glue.
Epoxy itself is glue that will hold to metal.
There are no health risks of epoxy glue,unless you ingest it.
I would use a two part epoxy.