Single crystal Elastic Constants (SECs) are fundamental to the understanding of the deformation behavior of materials. SECs define the elastic resistance of single crystals to external forces. Estimation of SECs are particularly important as single crystals find applications in semiconductors, sensors and turbine blades. Also, SECs directly relate to the bonding between the atoms and are most often used for validation of interatomic potentials developed. SECs are also essential for micro-mechanical modelling of various properties, for residual stress measurements using diffraction techniques and for interpretation of seismic data in the field of geological sciences. Though the necessity for estimating SECs is well established, standard methodologies for the estimation are limited and accompanied by complexities. The most common techniques used to measure SECs are resonant acoustic spectroscopy (RUS) and the Brillouin scattering and in both of these techniques sufficiently large single crystals are required. But for many of the inorganic compounds and engineering alloys it is difficult to grow a single crystal of sufficiently large length and also of the same composition as a polycrystalline counterpart. This led to the use of computational techniques and in particular first principle Density Functional Theory (DFT) simulations. Though DFT simulations are successful in estimating SECs for several inorganic compounds, the method fails for several new engineering alloys and also the SECs estimated using computational techniques require validation. This necessitates a need for a more robust method to determine SECs for any engineering material. Therefore, in this work a methodology is developed to determine SECs for any single phase material using laboratory X-rays and self-consistent models. And for this purpose, a universal loading fixture is custom buil t that is capable of perfo rming in-situ uniaxial/biaxial-tension/compression experiments by integrating it with a commercial laboratory X-ray diffractometer. In this talk, available literature on the methodologies used to measure SECs followed by the design and development of a Uniaxial/Biaxial Tension/Compression loading fixture will be discussed. Optimization of sample geometry is essential for accurate and reliable acquisition of experimental data and the talk also focuses on the optimized miniaturized sample geometry for in-situ X-ray diffraction experiments.