A method for designing and assembling a modular IT rack includes a manufacturer designing and constructing lightweight, modular corrugated cardboard modules/segments and corresponding banding and corner components that can be used to assemble the modular IT rack. A user/assembler of the modular IT rack assembles modular tray grouping and enclosure (MTGE) casing units using a first set of cardboard modules. The user constructs trays using a second set of cardboard modules. The user affixes cable support components to the sides of sub-groups of the constructed trays. The user encloses sub-groups of trays having the affixed cable support components within the assembled MTGE casing units to create MTGE blocks. The user vertically stacks the MTGE blocks having the tray sub-groups and the affixed cable support components enclosed within. The user aligns and secures the vertically stacked MTGE blocks in a fixed position using banding and corner components.