Clear E6000 is ok for a temporary installation. You can use something like Goo Gone to remove the glue and put a tritium vial in something else. People use Norland 61 for a more permanent installation. Cheule has a good video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nLdAZeSJSpw.html