As mentioned, the main difference between extruded acrylic and cast acrylic is basically the production methods employed in their manufacture. With regards to extruded acrylic, a discussion of how it is manufactured is outlined in an earlier article, and therefore does not bear repeating here. In the case of cast acrylic, the manufacturing process involves pumping methyl methacrylate monomer (MMA) into a mould made of glass. The mould together with the MMA is then submerged in warm water, therefore allowing the process of polymerization to take place. This process gives cast acrylic certain properties which are not present in extruded acrylic.