Modelling Foam Cube (pink PS)

Our one hundred and sixty-something cubes have all been specially made to have the same form and dimensions (40mm²). These four centimetre cubes, made in a multitude of different materials, are one of the stalwarts of the Materials Library, with a long and rich history. The cubes started their life back in the mid-2000s as one of the first sets of specially made objects for our Director Zoe’s PhD, which she used to explore people’s experiences of the density of materials as varied as tungsten, jelly and balsa wood. These cubes are used to encourage our members to think critically about how the materials they choose for their work might impact on people’s sensory and aesthetic experiences of everyday objects.

This blancmange-pink cube is an extruded polystyrene (XPS) modelling foam that is also commonly used for insulation in construction. Foams that are typically used for model-making include polyurethane (PU) foams, ethylene-vinyl acetate (EVA) foams, polyethylene foams like Plastazote, durable extruded polystyrene (XPS) and brittle and lightweight expanded polystyrene (EPS), to name a few.

Modelling foams are relatively cheap, light weight foamed polymers that are strong for their weight, with extra strength imparted by their foamed structure. This strength varies depending on the polymer used and whether a foam is open or closed cell, how small and densely packed the pores are, the geometry of the pores, and the manufacturing processes they have undergone, like their curing conditions and post-processing treatments. These properties will also determine how easily a modelling foam cuts, how much it crumbles or tears when shaped, and how fine a finish can be achieved with the material.

Engineers, prop and costume makers, architects and railway enthusiasts alike all use materials like this to create prototypes to test their ideas, or make lightweight but intricate facsimiles of real objects. Modelling foams are generally easier to cut and work with than solid plastics, metals and composite materials, so the maker can manually sculpt using foams saws, hot wire cutters, rasps and sandpaper, or use more dense modelling foams with digital tools like a CNC machine.