This is my first instructable, so I would love some constructive criticism :)
Step 1: Materials ...
2. Seashells. I was lucky to find these for $1 a basket at Dollar Tree. I only opened two baskets & didn't even use all of them, so I had plenty.
3. Craft foam, also $1 a pack at the Dollar Tree. I only ended up using most of a single cube, so I had plenty left over.
4. Hot glue gun & glue sticks.
5. Cutting board.
6. Sharp knife.
Since I already had the knife / cutting board but bought everything else, I think the whole thing cost me under $20 for the parts I actually used (I bought more than I needed).
Step 2: Cut the Foam
Step 3: Attach Foam to the Inside of the Cube
Lay your cube down on the front-facing side, and apply hot glue to the edges of the foam that will mate with the cube. When working with the foam, make sure any cut edges are on the back / in the open space; you want the nice, flat edges to mate with the cube and give you a flat work surface. Attaching with the cube face down will make sure the foam is flush with the face.
Once the foam is stuck to the inside of the cube, run a bead of hot glue along the seams. Don't worry about being messy, it'll be hidden by shells.
Step 4: Start Attaching Those Shells!
Start by layering your shells, biggest on the bottom, smallest on top. Make sure you overlap where the foam attaches to the cube. Be generous with the glue, any that squishes out can be removed with a paring knife / Xacto knife.
A little tip to hide glue bulges in the joints where shells meet is to use tiny shells on top.
To apply shells, I found it easiest to find the broadest, flattest portion of the shell and glue that part down first. Since the glue stays soft for a few minutes, you can then see where the rest of the shell touches the foam / cube, gently lift it up, pump a little glue under it, and press it back down.
Use long, skinny shells or large, broad ones to support smaller ones. Add plenty of depth. Don't limit yourself to just the foam corner, that's just where the focal point of each cube will be.
Step 5: Clean Up Your Glue, Mount on Wall and Enjoy!
Follow the mounting instructions included with your cubes.
Now go enjoy your beautiful new seashell wall art! And make good use of all the leftovers - waste not, want not! I saved the small baskets for a future project, and made good use of any leftover shells (I never did open the third basket).