Concrete form apparatus and method of using

A concrete form apparatus, comprising:

• a first component composed of a cardboard material that is rectangular in shape and includes at least three perforations along a lengthwise dimension of the cardboard material;
• and
• a second component composed of a core material having dimensions sized to fit within an internal cavity that is formed when the cardboard material is folded along the at least three perforations,
• wherein the second component is placed onto the first component, and the first component is folded along the at least three perforations to encapsulate the second component within the internal cavity to provide the concrete form apparatus,
• wherein the first component includes an inner surface facing the internal cavity, the inner surface defines at least one extension inlet, each extension inlet of the at least one extension inlet being a cavity extending away from the internal cavity and perpendicular to a surrounding area of the inner surface, and each extension inlet of the at least one extension inlet is configured to receive and engage a corresponding extension outlet of a coupling apparatus for connecting the concrete form apparatus to another concrete form apparatus.