The influence of microstructure on first order magnetostructural transitions will be studied along the processing chain from single particles to spark plasma sintered, hot compacted and PBF-LB processed powders. In-situ studies of stress, temperature and magnetic field induced transitions will be performed to correlate the nucleation and growth process with microstructural features that influence the transition mechanism and thermal hysteresis. These comprehensive analyses will allow a scale-bridging understanding of the transition to develop microstructural design pathways to tailor the multicaloric effect and hysteresis. (A03, A04, A10, A11, B01, B02, B08).