Abstract: Apparatus for measuring a workpiece which includes a support structure for carrying a longitudinally displaceable guide carriage, which guide carriage in turn carries a measuring feeler. To accommodate precise measurement of relatively large objects, without the requirement of an excessively large and heavy single support structure for the longitudinally displaceable guide carriage, the support structure is formed of a plurality of identical support elements. Each of the support elements are provided at the respective opposite end plates with mounting pins and recesses interengagable in a force form-fitting manner so as to align and connect the support elements in a precise location relative to one another. The end plates of the support elements are provided with grooved bracket structure to accommodate passage of the carriage past the junction of two support elements.