Cyclops and Glue

Seiko S-310 Two Component Adhesive

Do not worry, the instructions are also in English
and this is the same glue that is also used to fix Crystals to watch cases. A two component glue that gives you enough time to work after it is mixed. As with all two component glues, it is very important to mix the components 50 - 50.

The red tube contains the Hardener and the black tube the so called Base liquid. Remember to put the right cap on the right tube, otherwise they will be locked forever probably.
Adhering time given for this adhesive is

Clean parts that go together with alcohol to remove eventual dirt and fat.