foam-it! 5 rigid polyurethane foam - trial unit smooth-on not suitable for making 'squishies'. foam-it! series consists of two-component rigid foams that are versatile and easy to use. the mixture will expand many times original volume (depending on which foam-it! product you are using) and develop a uniform cell structure.developed for a variety of industrial and special effects applications, these foam products can be pigmented to achieve various color effects. foam-it! foams are especially useful as reinforcement for hollow castings. foam-it! 5 - mix ratio: 1a:1b by volume - approx. 10x expansion; pot life: 1.5 mins; cure time: 2 hrs; color: beige read the msds before using.