Environmentally friendly lightweight knockdown building block set

An environmentally friendly knockdown building block set comprising:

• A cardboard shipping box;
• Six to eighteen main blanks within the shipping box formed of recycled cardboard, each main blank configured to form a three dimensional base block of the environmentally friendly knockdown building block set which base block includes four connecting slots therein that are as wide as the thickness of the base block;
• Twelve to thirty-six coupling blanks within the shipping box formed of recycled cardboard, each coupling blank configured to form a three dimensional H-block of the environmentally friendly knockdown building block set which H-block includes two connecting slots therein with each slot located between two legs of the H-block and as wide as the thickness of the H-block;
• Wherein the connecting slots of each base black and each H-block allow for receipt of, and interconnection of, the base block or H-block with a connecting slot of an associated base block or with a slot of an associated H-block forming a notched connection for the base blocks and H-blocks of the environmentally friendly knockdown building block set;
• Wherein at least the base blocks and H-blocks include an inking pattern using plant based environmentally friendly inks;
• and
• Wherein the cardboard shipping box includes at least one panel block member configured to be an integral component of the play set and configured to be integrated into structures formed by the base blocks and the H-blocks of the set, and wherein each panel member includes perforations to form openings to receive the legs of the H-blocks.