The present contribution deals with the design of a monolithic weighing cell for the realization of a further developed mass comparator for 1kg-standards. The monolithic structure with semicircular flexure hinges is approximated by a rigid body model. The resulting equations can be used as design equations for a first layout of the mechanical system. Existing adjustment concepts for the stiffness characteristic and the sensitivity to quasi-static ground tilt are included. They are extended by the novel approach to manipulate adjustment masses on the levers of the linear guide. Based on this concept, an optimal design for the weighing cell is determined. The comparison to a geometric non-linear finite element model reveals the limits of the rigid body model. By a parameter study of the adjustment parameters in the finite element model, the stiffness and tilt sensitivity were reduced by five orders of magnitude compared to the unadjusted weighing cell.