This paper presents the design of an assembly to support the Hectochelle multi-object spectrograph grating. The grating consists of two mosaicked, 420 mm by 320 mm by 74 mm thick, 110 line/mm echelle grating segments, nominally operated at a 72 degree angle of incidence. The fact that the grating consists of 2 segments that must be co-aligned to within 0.27 arcsecs creates a challenging design problem. After much preliminary examination, two support deigns were studied, one utilizing Invar, and the other, selected for development, using a Zerodur support structure. The trade study to select the final design is discussed. The Zerodur design was selected because it maintained higher grating stability throughout the operating temperature range than the Invar design. The Zerodur design concept is discussed in detail, including the results of finite element modeling that shows system feasibility.