My Wife and I recently made some Geode Tables with no substrate from epoxy Art Resin. They turned out beautiful! After letting the table set for 3-weeks I inverted the 21’x 19″x 3/4″ thick table on 4 large plastic cups to drill the bottom for the threaded insert to attach the legs. I had the table sitting on the cups for 3-4 hrs while the epoxy set around the insert. After the epoxy set, I turned the tabletop back over on the work table and noticed the cups had made an impression in the tabletop. Disaster! My question is, What Resin do I need to use to make these Geode tables so I have a much harder finished product? Do I need to use a deep pour resin or casting resin or an add in product to make the resin harder? I did mix the resin aggressively for 4 minutes prior to pouring it into the mold. Thanks in advance for your help.