I once saw a bar that was lined with coins then had some sort of clear acrylic poured over it to create a smooth glass-like surface. I am considering doing something similar with small river rocks and pebbles. Possibly another project with old keys. I was wondering if anyone knew what the best product to use is and where I can find it.

Google: "clear casting resin" and you'll find what you need. Check out a product by Tap Plastics called Clear Lite. www:tapplastics.com