I came up with these as centerpieces for an Australian-themed birthday I helped put together.
Step 1: Get Supplies
This centerpiece can be altered to different colors, different material.. limitless really but here's what I used:
silk evergreen plant
large plastic bowl
Step 2: Make the Base
The base is just a dome-shaped piece of styrofoam.
I cut mine with a hacksaw. Be careful if you use saws or knives.
Then I hotglued it to the bottom inside of the plastic bowl
Step 3: Branches and Coral
Spray paint your tree branch OUTSIDE. Try to look for a branch that mimics the shape of coral, something unique. I found mine in a park. I think it might actually be part of a root system.
Also during this time you will assemble your little coral pieces.
One awesome affect is to hot glue packing peanuts. DO THIS OUTSIDE WITH A OUTDOOR EXTENSION CORD. Get a nice ball of them (softball sized) glued together and then spray paint that ball ALSO OUTSIDE. The paint eats away at the Styrofoam and gives it a neat texture. Do not get too close to it while you're spray painting and gluing.
Another piece I made is by balling up newspaper, ductaping it into a ball about the size of a bar of soap, then hot gluing pieces of silk evergreen to it (the spiky kind) and the spray painted the whole thing.
My tissue paper piece is a paper tissue pom pom I made.
Step 4: Assemble
Okay keep the hot glue coming on this part.
You will want to first mount the branch in the middle of the styrofoam dome. Lots of hot glue here! For extra support I duct taped metal wires at the end to pierce the styrofoam and add support (spray paint after you would add wires).
At this point you can glue on some rocks to the dome as well. Just to have a rocky-looking base.
Pour on the sand. I used 1 lb white decoration sand. Just make sure you cover your dome.
Then add your smaller coral pieces in here. I also had added support by just poking a 3" wire in the styrofoam dome and sticking in my coral. They should go right in.
Step 5: Enjoy
You can dress it up a little more by adding dry sea stars or silver dollars or whatever shells you have.