How much Deep Pour Epoxy do I need to fill a mold?

Work from the mold's surface area and depth, the same way the Deep Pour Epoxy Calculator does (https://www.bestbartopepoxy.com/pages/deep-pour-epoxy-calculator); we size pours by length x width (or diameter) and depth, not cubic inches. Convert the mold opening to square feet, then apply the coverage of a 1.5 Gallon kit of UltraClear Deep Pour Epoxy: 10 sq ft at 1/4", 5 sq ft at 1/2", 2.5 sq ft at 1", or 1.25 sq ft at 2". For several castings, add up the areas of all the molds and round up to the next kit size.

A 24" round x 2" deep silicone mold is 3.14 sq ft and needs about 3.75 gallons, so two 1.5 Gallon kits aren't enough; you'd need a third. Two 1"-thick 15" clocks, one square and one round, total 2.9 sq ft; a 1.5 Gallon kit only covers 2.5 sq ft at 1", so order a 3 Gallon kit.

When you pour, fill the mold in 1/4" passes so you can pop the air bubbles in each thin layer, pouring right over the previous pass until you reach 1" total, then wait 12 to 24 hours before the next 1" layer. Deep Pour can go 2" in a single pour, but newer users get the best results with 1" layers. Don't mix more than 1.5 gallons in one batch: a 1" pour over 3.14 sq ft takes 1.9 gallons, so mix two batches.

Deep Pour Epoxy Instructions: https://ultraclear.helpscoutdocs.com/article/840-deep-pour-epoxy-instructions