Step 1: Materials List
Plastic or plastic coated cups to mix in
Something disposable to mix with (I used popsicle sticks)
A well ventilated area
Bottle caps to set in the resin
If you want your coasters to be colored, you can get resin dyes as well.
Links above are just some places that I have found these items, not necessarily where I got them from.
Step 2: Get a Mold and Prep It
To prep your mold, spray a thin coat of mold release on your mold. Let it dry before casting your resin.
Step 3: Prep Your Bottle Caps
Step 4: Pour the First Layer of Resin
Step 5: Insert Your Bottle Caps and Pour the Top Layer of Resin
Step 6: Finishing Your Coasters
To make your coasters smooth, use your sandpaper to remove any bubbles or imperfections (aka the meniscus that has formed around the top rim of the coaster) that may have appeared during the initial pouring. I used 220 grit sand paper. It's not extremely important what grit you use, but I wouldn't go any courser than a 200 grit. All you want is to remove the bubbles and not make scratches that are too deep. Once you've sanded the bubbles and imperfections out, wash the coaster in water to remove all of the resin dust. Make sure that it's clean. The dust left on the coaster will get embedded in to the coaster after you put the next layer of resin on and will make this step useless. After completely drying the coasters, place some paper on your work surface to keep it clean. On top of the paper, place your coaster on top of the object mentioned earlier (see picture again). Mix up another ounce of resin using about double the catalyst that you used for the base layer of the coaster (I used 10 drops of catalyst for 1 oz of resin). Pour a thin layer on top of the coaster. You can smooth it out to the edges using your stirrer. Once you've made a nice coat on top, coat the sides by using your stirrer to place the resin on the sides of the coaster. It will drip, which is why you covered your work surface and used something to elevate the coasters. After about 5 minutes, use a popsicle stick or anything else that you can throw away to remove the beads of resin that have pooled on the underside of the coaster on each of the 4 sides. You now have removed most of your imperfections. Pictures 4 and 5 of this step show bubbles on the side of the stone coaster and their appearance after the first coat of finishing resin. It's likely that I will have to repeat this step (at least for that coaster), but it's definitely an major improvement.
Step 7: Enjoy Your New Coasters
Thanks for reading!