The staircase is constructed of laminated 3/4" plywood sheets, and all of the components are interlocking using mortise and tenon joints instead of fasteners.  Photos from An Intern Architect Builds a Home For His Growing Family on a Strict Budget

Photos

The staircase is constructed of laminated 3/4" plywood sheets, and all of the components are interlocking using mortise and tenon joints instead of fasteners.