def group_mat_params(**params) -> tuple:
    """
    Groups and returns all input material parameters as a 3-tuple
    of dictionaries.

    Returns
    -------
    tuple
        3 dictionaries for Young's moduli, Poisson's ratios 
        and shear moduli.
    """
    PARAMS = {key.upper() : value for key, value in params.items()}
    keys = list(PARAMS.keys())
    E = {key : PARAMS[key] for key in keys if key[0] == 'E'}
    NU = {key : PARAMS[key] for key in keys if key[:2] == 'NU'}
    G = {key : PARAMS[key] for key in keys if key[0] == 'G'}
    return E, NU, G