Attach a frame of 1-by-2-inch lumber all around the countertop to encase the liquid acrylic until it hardens up. Use small, headed nails to attach it to the wooden base of the countertop. Don't pound the heads of the nails all the way flush with the wood, to make it easier to remove the frame when the countertop hardens. If the objects you plan to embed in the resin countertop are larger than one-inch high, use 1-by-3-inch or 1-by-4-inch lumber for building the frame to accommodate their larger sizes.
Clean the surface of the counter with regular household degreaser cleaner, following the manufacturer's instructions.
Mix the acrylic resin with the hardener, exactly following the instructions on the label. Use an eyedropper, if necessary, to measure the hardener to ensure the proportions are exact. Mix in a non-waxed disposable cup using a wooden craft stick. Mix slowly by cutting the stick through the acrylic to minimize the number of air bubbles you introduce into the mixture.
Pour a thin layer of the mixture onto the countertop, approximately 1/2 inch thick. Allow the mixture to harden to the consistency of gelatin, following the manufacturer's label directions.
Set the objects you wish to encase in the acrylic on top of the almost-hardened first layer of acrylic.
Mix a second batch of acrylic resin, carefully following label directions. Some brands of acrylic resin use a different proportion of hardener for the second and succeeding layers, so consult the label before mixing each successive layer. Allow it to harden or cure following the manufacturer's recommendations.
Continue building layers until you reach the top of the wooden frame, then allow the acrylic to set up for the manufacturer's recommended length of time.
Remove the wooden frame from around the edge of the countertop.
Sand the surface and sides of the countertop lightly, to smooth out any imperfections. Use 200-grit or finer sandpaper and do not exert much pressure; you don't want to mar the surface.
Encase the edge of the countertop with decorative trim or molding, if desired, for a finished look.