An apparatus guides first and second assembly components into a predetermined configuration, each assembly component including an opening. When the assembly components are aligned into the predetermined configuration, their openings align to define a cavity for receiving a stepped dowel to fasten the components together. The guiding apparatus includes a stepped dowel member having successively-smaller dowel sections, and a collar member floating around the base of the stepped dowel member. The stepped dowel member tip can be passed through the first assembly component opening and inserted into the second assembly component opening, drawing the components into the predetermined configuration. When the components are aligned into the predetermined configuration, the collar member engages the first assembly component opening and the stepped dowel member engages the second assembly component opening. The guiding apparatus can be disengaged, freeing the dowel-receiving cavity to accept a stepped dowel for fastening the assembly components together.