A system for assembling a plurality of toy building pieces into a structure or other item, the system comprising: a first structural assembly component having at least a portion of its surface visible in an assembled orientation, the first structural assembly component having a first female cavity with an open end, the cavity having an extending shoulder portion, and the cavity having a retaining section adjacent the shoulder portion opposite the open end; a second structural assembly component having at least a portion of its surface visible in an assembled orientation, the second structural assembly component having a second female cavity with an open end, the cavity having an extending shoulder portion and the cavity having a retaining section adjacent the shoulder portion opposite the open end; and a male connector portion having a first extending end and a second extending end, at least one of the first or second extending ends of the male connector portion having at least a pair of legs, each of the at least a pair of legs being biased to a first extended position from each other of the at least a pair of legs; and the male connector portion being configured to be slidably received at its first end in the first female cavity of the first structural assembly component and configured to be slidably received at its second end in the second female cavity of the second structural assembly component, such that the first structural assembly component is abuttably connected to the second structural assembly component; characterised in that the first and second cavities each have a closed end remote from the open end, the shoulder portions each include an inclined ramp extending toward the open end, and the male connector portion is configured such that, for each end having at least a pair of legs, the legs are slidably receivable within either the first female cavity or the second female cavity so as to deflect opposite their bias along the inclined ramp, and to biasedly re-extend into the retaining section upon being received past the ramp, such that the male connector is biasedly retained within the receiving first or second female cavity. a first structural assembly component having at least a portion of its surface visible in an assembled orientation, the first structural assembly component having a first female cavity with an open end, the cavity having an extending shoulder portion, and the cavity having a retaining section adjacent the shoulder portion opposite the open end; a second structural assembly component having at least a portion of its surface visible in an assembled orientation, the second structural assembly component having a second female cavity with an open end, the cavity having an extending shoulder portion and the cavity having a retaining section adjacent the shoulder portion opposite the open end; and a male connector portion having a first extending end and a second extending end, at least one of the first or second extending ends of the male connector portion having at least a pair of legs, each of the at least a pair of legs being biased to a first extended position from each other of the at least a pair of legs; and the male connector portion being configured to be slidably received at its first end in the first female cavity of the first structural assembly component and configured to be slidably received at its second end in the second female cavity of the second structural assembly component, such that the first structural assembly component is abuttably connected to the second structural assembly component; characterised in that the first and second cavities each have a closed end remote from the open end, the shoulder portions each include an inclined ramp extending toward the open end, and the male connector portion is configured such that, for each end having at least a pair of legs, the legs are slidably receivable within either the first female cavity or the second female cavity so as to deflect opposite their bias along the inclined ramp, and to biasedly re-extend into the retaining section upon being received past the ramp, such that the male connector is biasedly retained within the receiving first or second female cavity.