Adding seashells to your decor is a sure way to create a coastal or nautical feel in a room. You can even add seashells to something practical rather than purely decorative, such as a tabletop. Because seashells are fairly delicate, if you want to actually use the table, you need to protect them with something more stable. Glass and epoxy resin are both suitable for this; glass will allow you to take the table apart if desired, and epoxy embeds the seashells in a layer of resin that permanently attaches to the tabletop.
Clean the tabletop and paint it a desirable background color or seal it with a clear sealer. This is particularly important if the table is wood and you want to use resin, since it will prevent bubbles from coming out of the wood.
Cut wood strips or decorative wooden trim so that you have enough strips to go around the perimeter of the tabletop. The strips need to be slightly wider than the height of your largest shell so that all of the shells will be covered. If you decide to use glass, either cut a notch into the inside top of the wood strips or use two strips together, with one of the strips being narrower than the other to accommodate the width of the glass. This will make a sort of "shelf" for the glass to rest on. To cut the wood pieces, a saw that leaves a fairly clean edge is best, such as a coping saw. Use a miter box on the ends if you'd like mitered corners -- corners that meet at an angle.
Paint or stain the strips to either match or contrast with the rest of the table.
Glue the strips into place. If you are using two strips for glass, the narrower strip goes on the inside. This border should feel very sturdy when the glue has dried. If needed, add some fnishing nails along the strips. Use a nail set to conceal the tops of the nails if needed, and fill the holes with wood putty. When using resin, the strips of wood will contain the resin, which is liquid initially. It's important to get a good seal between the strips and tabletop to prevent leaks.
Arrange the seashells as desired on the tabletop.
Glue the seashells into place. A plain white or craft glue is suitable for most situations, but you may need something stronger, especially if the tabletop is not wood. In this case, try a silicone glue or two-part epoxy.
Measure the inside dimensions of the tabletop to determine how large the glass piece needs to be. Transfer these measurements to the glass piece if it's larger than the finished size.
Hold a straightedge along each cut that you want to make, run a thin line of cutting oil along the line -- or lubricate the glass cutter's blade -- then use the glass cutter to score the glass. Snap the pieces apart. You can use your hands, but a running pliers will help you make a clean snap. Retailers that sell glass will often cut pieces to size for you.
Smooth down the sharp edges with a piece of wet emery cloth.
Clean the glass thoroughly and lower it into place. If you want the glass to be more permanent, apply clear caulk around the edges of the notch or inner wood strip before adding the glass. Silicone caulks are very strong, but acrylic caulks are easier to work with if you are inexperienced with using caulk.
Determine how much epoxy resin you will need to mix at a time. The package will most likely have instructions regarding coverage. Pour about 1/8 inch to 3/8 inch at a time for each layer. Epoxy cures through a chemical reaction and gets very hot.
Mix clear epoxy resin according to the instructions. The catalyst activates the resin, which starts the curing process. Mix with a disposable wooden stick in a disposable container. Be thorough, but don't stir vigorously, since this will create bubbles.
Pour a layer of resin into the tabletop. Be careful; pour evenly and pop any bubbles that you see as soon as possible. You can use a toothpick; a heat gun will also help with bubbles.
Mix and pour another layer of resin once the first layer has begun to set. Repeat until you have filled the area between the wooden strips and covered the seashells with resin.