Place the large items on a glass plate and cement them.
I used ultraviolet light activated resin. It's easy to adjust the solidification time by a black light.

Applying ultraviolet light activated resin.

Then, place small items such as beads, coral sands and such.

When the resin gets dried, shake off materials that were not stuck.

Repeat this process.

Make sure everything is stuck together.

After you cement it on the larger plate, cement the glass dome.

Finished!