You have probably heard about "100% Cell Cast Acrylic" and how this is the only kind of acrylic companies use. It is true that cell cast is the preferred option. But many people don't even know what it means. And even fewer people have actually seen an example of the "cell". Here is a quick summary of what cell cast acrylic is and pictures of what the cell actually looks like.
Acrylic is made two main ways - Cell Cast and Extruded. Cell cast involves creating a single "cell" into which the acrylic polymer is poured or injected into. The cells consist of very heavy glass plates set apart as wide as the finished acrylic sheet. The entire perimeter is sealed with a flexible membrane. Once the acrylic polymer cures, the glass plates are removed and a sheet of solid acrylic remains. The flexible membrane is then trimmed off, much like the crust of a slice of bread. It is time consuming and expensive but yields the best quality sheets.
Extruded acrylic is made like toothpaste is squeezed out of a tube. Much faster since it is a continuous process. Extruded acrylic is significantly less expensive and not nearly as high quality. We use only cell cast acrylic for all structural components such as walls, bottoms and tops. We do use extruded acrylics for non-structural, cosmetic applications such as coloring.