The EP37-3FLSP polymer system is an optically clear, flexible, low viscosity two-part epoxy system for large volume castings. It features a long working life, low exotherm during cure, and very low shrinkage, as well as excellent dimensional stability. The EP37-3FLSP has a convenient non-critical mix ratio of 2:1 by weight. The “pot life” after mixing exceeds 10 hours. Volumes as much as one gallon and more can be readily cast at room temperature without undue exotherm development.