This is a tutorial that will show you how I made this coral decoration for our Under the Sea theme event.
Step 1: Starting Out!
Okay, so I was going to create an "under the sea" theme for our church summer camp and I wanted to create something a bit more interesting than the "construction paper wall and crayon look". So I decided to try making some sea coral out of spray foam. I laid out some tin foil. Some I laid flat, and some I cupped into a planter to create a curved shape. I knew I wanted the coral to have different levels and lots of texture. I bought some spray foam (insulation that expands) and decided to try out the "cup" coral this way. USE GLOVES!! It's very sticky! Spray it into the cup forms and also into little oval shapes on the tin foil and spray as many as you can get out of the can and then let it sit for about 15 minutes. You can try to shape them by bending the tin foil underneath into "arches" so that it starts to take the form of a "cup" type coral piece. Like I said, after you like the shape, let it sit for a few minutes.......Don't let it dry completely just yet, but when it's slightly stiff and no longer sticky to the touch, try to remove the tin foil from the backs of each piece. If you wait too long, the tin foil will be permanently part of the coral...you might like that, but I didn't, so I pulled off each piece and by doing so, it then creates even more bubble texture on the underside which I REALLY liked the look of. It gave it an organic look and that was perfect for the realism. Then let those "cups" or pods..whatever you want to call them, dry completely (hour or more).
Step 2: Build the Base
Next, I took some scrap styrofoam pieces that I had and cut strips off of it. Then I duct taped them into a teepee shape. It doesn't have to be super strong at this point. It just needs to have something for the pods and foam to stick to later in the future steps. Then I added some newspaper to fill the empty space inbetween the teepee stands. I secured them all to the base styrofoam sheet and then used tooth picks to stab into the pods and then into the stands for the teepee. Again, this doesn't need to be super sturdy, but it does need to be "in place" so that when you spray the remaining foam it has something to latch on to. After it was generally in the formation that I wanted, I got some more spray foam in a can and decided to go layer by layer, building up the texture. What I realized quickly is that the foam doesn't like just hanging there on a smooth surface. It just drips off. So the first can, I added just random strips of spray foam to stick to the newspaper and stands so that the next layer could have ledges to hold on to. I used the whole can and let it dry (another 30 mins). After that was mostly dry, I got the next can of spray foam and then went to town, spraying it everywhere I could to build up a natural pattern and let the foam expand into all the crevices and stiffen. Make sure to spray under each pod so that it can support the weight and not rely on the teepee stands for all the weight of the pods. Let that dry and then keep adding layer upon layer until the desired amount is on the coral mound. It'll expand, so keep that in mind as you spray. If you use criss cross patterns while spraying, the foam with expand and harden and create a "web" type structure that'll hold itself up once it's hardened. Then just spray the next can into all the crevices to make it a solid look. Let it all dry thoroughly.
Step 3: Start to Paint...
Once the whole mound is dried, take it outside and get a spray paint color of your choice. I used pinks and purples for mine. Go online and look up pictures of real coral for inspiration. Then start painting. I used the darker colors for the underside of each pod and inside the crevices to help add depth to it.
Step 4: Dry Brush
Next I used a dry brush technique to add the final details to it. Actually the details should already be there, this step just helps emphasize it visually. Use a dry paintbrush and dab it into just a little bit of white paint or a lighter shade of whatever color you chose as your base color and then wipe off most of it on a newspaper so that barely any paint is on the brush, then brush lightly in one direction across the surface of the coral so that just the details pick up the highlights of the texture. You can do the same for the underside with a darker color if you'd like. That's the fun part because it's completely up to you how you want to texture and color it. :) I added some blue highlights underneath and even into the top just to add some interest and detail.
That's it! You're done! You can coat it with a spray finish if you'd like, to help protect it, but just let it all dry and you have a new coral prop that only costs the price of spray foam, styrofoam, tape, paint, and time. :)
Hope this was helpful. :)