This is a tutorial for a mosaic table top made mostly of sea glass. It was fairly difficult to make, but I started out as a beginner and was able to execute it.

This project is time consuming but makes an amazing and personal gift. I made this for my sister for Christmas and I cant wait for her to see it! Over the last 18 years we have spent countless hours scouring the beach and climbing cliffs to collect this sea glass and I finally found a good way to display it.

The round tabletop with grey grout has a more even top made up mostly of flat or thin pieces of sea glass and shells
The rectangular tabletop with black grout is has a bumpy top and features broken pottery and thick pieces of sea glass of various sizes (this was my practice piece for me)

Step 1: Supplies

Table: Select a table you would like to repurpose. You can put your mosaic directly on the original tabletop or replace it with cement backer-board (I used one that was 1/2 inch). If you use the backer-board make sure it is sufficiently supported when on the table (see here)
Mosaic Tiles: If the table doesn't have a lip then you will need to create your own. I used 1 inch glass mosaic tiles.
Sea glass and Other Beach Items (ex. shells, stones, pottery, etc.)
Tile Adhesive
Grout: I used unsanded grout because of how close together all my pieces were and it worked well. If you color your own grout make enough for the whole project because it will be difficult to match the same color again.
Sealant: Decide if you want one that will leave your pieces shiny (I suggest this for sea glass)
Tiling Sponge
Tile Trowel: Use a tile trowel if laying large mosaic pieces over a wide area of adhesive at a time.
Grout Bag (for tile adhesive): This works better for small pieces since it give you more control. You can get these bags from a hard wear store or use a pastry bag (used for frosting) from a cake store. In a pinch you could try cutting the corner off a large ziplock bag.

Step 2: Prep and Clean Mosaic Materials

Pieces can vary in size but should not be thicker than the lip of the table if you want a flat(ish) surface. Select the shells you use carefully. They should be strong and flat. Fill any cavities they have with grout. You can dip shells in lacquer (or clear nail polish) to fortify them and prevent them from being colored by dark grout.

Clean and dry your mosaic materials thoroughly before using. My favorite way is to soak the pieces in denture cleaner (full tutorial here). You could also wipe them with rubbing alcohol or soak them in a soapy-solution. I organized my pieces by color.

Step 3: Make a Test Piece

If something is going to go wrong you don't want it to happen on your table so I suggest doing a couple small test pieces. I did mine on $.75 tiles. It was a good thing I did a test because as you can see in the picture, the grout colored my starfish. The entire rectangular table was my practice table before I did the round one (my sister would kill me if I wasted her sea glass collection)

Step 4: Tile the Rim

If you get a table that already has a lip then this may not be necessary. Apply a thin layer of tile adhesive and secure the tiles along the rim of the table, so that a rim is formed by the portion of the tile that comes past the table side.

You could also create a frame for a rectangular table to sit in with 1-inch tall strips of wood that you nail or glue to the surface before you begin tiling. If you do add a frame, make sure to stain or paint the frame to match the rest of the table before you begin tiling.

Step 5: Lay Out Sea Glass

Some people cut cardboard to match the size of their table and lay out the tile/glass design out on that before transferring it to the real piece (see here). I decided not to do this and I did not have any trouble. The design should look similar to a puzzle, but with small gaps between the pieces for the grout. I decided to create the center of my table separately so that I could get a perfect circle and would have a better angle when making it. I used a compass to draw my circle on a thick piece of cardboard and then glued a circle of parchment paper on top of that. I then applied the tile adhesive on top of the parchment and added my glass. When it has completed dried I peeled it off the parchment and glued it to the center of my table

Step 6: Lay Tile Adhesive

You can use a trowel to lay the tile adhesive (click here for a more detailed tutorial) but this may be difficult if you are using small mosaic pieces and doing small areas at a time. My preferred method is to fill a grout bag with the adhesive and squeeze it onto the table because it gives you more control over the location and depth of the glue.

Step 7: Create the Mosaic

Start adding pieces to your mosaic. Push in different sized pieces at varying depths to achieve a flat top that is level with the top edge of your tile border. Be careful to immediate wipe off any adhesive that sticks to the top of your mosaic pieces. I used a paint stick to press on the table top to help me achieve a flat-ish surface. Allow tile to set for at least 24 hours (or longer if it is damp weather). Take a nail and scratch off any adhesive that got onto your pieces.

Step 8: Grout the Table

Apply grout to the table by smoothing it between the pieces of the mosaic (I used my fingers) and let it sit for at least 15 minutes (click here to view another tutorial)

If you used cements backer board when you will also need to put a thin layer of grout on the underside. I rubbed on watered-down grout with a sponge and then went over it with a clean sponge after the grot was dry. Apply sealer after 2 days.

Step 9: Continue to Clean the Pieces

Once the grout has set for 15 minutes, start by cleaning off the excess grout with a dry paper towel. Shake/blow the dust off the piece, and then use a large wet sponge to continue to clean the grout of the tiles. Once the grout has dried overnight, wipe the tiles with a dry cloth to remove any haze left behind by the grout and give it another once-over with the sponge. If you aren't satisfied with the look yet, below are a few more techniques you can try:

Go over the table with a small sponge than can get between the pieces between
Put paint thinner (ex. mineral spirits) on a small sponge and scrub the mosaic pieces
Take a nail and scratch away dried grout
Use a drill with a brush attachment to get grout off pieces
Use soap, water and a scrubbing brush. What got me the best results was when when i poured a little sand on the surface and scrubbed/rinsed clean. Only do this after the grout has had at least 24 hours to dry.

If your scrubbing reveals some of the glue then use a toothpick to apply more ground to the area.

Step 10: Finish the Table

Let the table dry for at least 2 days before applying sealant.

Grout and/or stone sealer: This sealant is necessary to protect your grout from staining and your tabletop from ware. Unless you buy one that specifically says it will add shine, your piece will look as it did dry, before the application. I used one that promised a "wet look."
Polyurethane: If you want to give your glass an extra shine you can apply polyurethane. I suggest you take the time apply it with a small brush to the individual pieces rather than painting a layer over the whole table because when I tried this on a test-tile tiny bubbles formed on the grout.

After that you are done and can enjoy your table. I have more sea glass pieces here and this site has some great jewelry.