portable apparatus for automatically constructing prefabricated stud walls or other frame structures from standard materials . elongate studs are placed transversely at spaced intervals between a pair of elongate wall plate members by a reciprocatingly rotating stud - selecting mechanism and a linearly reciprocating spacer mechanism . as each stud is placed between the plate members , it is automatically nailed thereto , forming a portion of the wall frame , after which the completed portion of the frame is advanced an incremental distance along an assembly structure by the spacer mechanism , which pushes on the newly nailed stud to advance the frame to a position for nailing the next succeeding stud , and so forth in automatic cyclic fashion . a semi - automatic sheathing fastener mechanism includes a plurality of fastener guns and an automatically controlled actuation mechanism for placing fasteners at predetermined locations . apparatus is provided for varying the spacing between wall plates and for reducing overall width of the apparatus for legal highway transport . the apparatus includes self - contained electrically - powered pneumatic and hydraulic systems , and fluid - operated control systems .