This tutorial will show you how to make decorative bottle cap coasters with an epoxy resin (liquid glass) coating. These make great gifts as well as beautiful home decorations.

Some of the images in this tutorial will be drawings as I was not able to take pictures during some parts of the process.

This is an offshoot of my previous instructable: Bottle Cap Drink Coaster

Materials needed:

Rust-Oleum Parks Super Glaze Ultra Gloss Epoxy (or an epoxy resin of your choice) - Home Depot
Spar Varnish, Polyurethane, or some type of clear coat to seal your wood - ACE Hardware
- NOTE: You can even use a small amount of the epoxy resin you buy and brush it on like a varnish or clear coat. (This is in the directions of the Parks Super Glaze. However, something like a spar varnish gives a nice color.)
Sea Shells - Craft stores like Jo Ann Fabrics, Michaels, etc. or if you have some from a vacation.
Sand - I got mine from the lake my cottage is on but you could find sand at a craft store as well.
Masking tape - many hardware stores have it for sale.
Elmer's glue or wood glue - any hardware store.
Small brush - to apply the varnish.

Tools needed:

Hand held power saw
Plunge base router with a straight bit
Small brush

Step 1: Obtain Your Wood, Cut, and Router

For my coasters, I used 0.75'' thick pine boards and cut the coasters to 4.25'' by 4.25'' squares using a hand held power saw. This allows a nice wood border and adequate space for the shells.

Once the wood is cut, use a plunge base router with a straight router bit to router out a square in which the shells will reside. For my bottle cap coasters, the routed area was 0.5" deep. Using sea shells, I had to go a little deeper since the shells were slightly taller than bottle caps. Just measure the height of the largest shell, and go a little higher than that height so the shell does not peak through the surface of the epoxy resin.

In order to determine a nice path for the router, place the shells on top of your square piece of wood and then use a pencil to trace an approximate rounded square around the caps. Set the depth of your plunge base router and then begin to remove wood from within the area you traced. See the first image above to see how I keep the wood stationary when using the router.

Step 2: Place Shells, Adjust, and Seal the Wood

Place your desired shells into the routed area of the coaster to see how they sit. If they are not fitting nicely together, use your router to adjust the edge so as to allow all of the bottle caps to fit nicely inside. Do this for the height as well. Look at the coaster with the shells at eye level to see if any of the shells are rising up out of the coaster.

Next, apply some type of sealer all over the freshly cut and routed coaster before doing anything else. I like to use the gloss spar varnish from ACE hardware (see above). I would suggest applying about 3 to 4 coats. Make sure the area where you routed is coated well as this will prevent the release of bubbles when you pour the epoxy resin (liquid glass).

Step 3: Add Sand to the Bottom (optional)

This is optional but I did it since it adds a nice look. Gather some sand either from outside or the store. If you are using sand from outside, I would suggest cleaning it first just to be safe. You could place it in a small amount of bleach with with a rinse afterwards. Then let it dry.

Once dry, take some wood glue or Elmer's glue and apply a thin layer to the bottom of the routed area. Spread it out using a brush. You do not need a lot. Just a thin layer on the bottom. Then, take your dry sand and pour some into the routed area. Let the the glue dry for a while and then remove the excess sand by turning the coaster over and dumping the sand out that did not adhere to the glue.

Step 4: Level the Coaster, Pour Some Resin, and Place Caps In

Obtain some epoxy resin. I like Rust-Oleum Parks 1-qt. Gloss Super Glaze Finish and Preservative from the Home Depot (see above).

Before pouring the resin, be sure to wrap the edges of the coaster in 1 to 2 layers of masking tape. This allows you to remove excess resin before the resin completely cures. In addition place the coasters on a small piece of wood so that they are slightly raised above the surface (See diagram above). BE SURE that the surface is level (or as level as possible) before pouring. This allows for the formation of a smooth level surface on the top of the coaster. The resin will self level once it is poured hence the need for a level surface.

Following the directions for the epoxy resin, pour about 1/16'' or just enough so that you could place the shells in the resin and they would not be completely submerged. Then take your shells and place them into the freshly poured resin (See diagram above). This prevents the air from remaining trapped underneath the shells say if you were to glue them down first and then pour the resin. Over the duration of the curing process, the trapped air from under the shells would release causing large bubbles to appear at the surface of the resin.

Allow this to harden (not completely cure) and then pour another coat. Make sure to pour so some drips/spills over the edges of the coaster. Again the resin will self-level and the resin along the edges of the coaster can be removed (once fully cured) by peeling the tape off. It helps to use some type of spreader during the pouring process. I like to save old gift cards and hotel room keys. You can use these to help move the resin. Sorry for the absence of any pictures or videos for the pouring process. I will have to take/make a vid for this part.

Note: In between pouring layers and in general when using epoxy resin, make sure you keep the coaster covered. This prevents dust, insects, etc. from settling on top of the hardening resin. Now you don't have to immediately cover the coaster. You can work with the resin for a while. For example, you can use a propane torch or your breath to release any large bubbles that may have formed during the pouring process. This is also explained in the directions that come with the resin.

Step 5: Cover Your Freshly Poured Coaster

I know this was a note in the previous step but just wanted to include it as a reminder.

Find a box or construct/use something to place over your freshly poured coasters. This will help to prevent dust from settling on top of the resin surface while it is curing. I use cardboard boxes and have not had any problems. Make sure to place a note on top of the box saying DO NOT REMOVE or DO NOT DISTURB just in case. You worked hard to make these!

Step 6: Enjoy Your Newly Made Coaster!

After the resin has fully cured, enjoy your newly made custom coaster! Use it as a decoration or as a gift for someone special. What is nice about these coasters and this process is that you can customize the coaster to your liking. I hope you enjoyed viewing this instructable.