Geometric realizations of curvature models by manifolds with constant   scalar curvature
  We show any Riemannian curvature model can be geometrically realized by a manifold with constant scalar curvature. We also show that any pseudo-Hermitian curvature model, para-Hermitian curvature model, hyper-pseudo-Hermitian curvature model, or hyper-para-Hermitian curvature model can be realized by a manifold with constant scalar and *-scalar curvature. 
M. Brozos-Vazquez, P. Gilkey, H. Kang, S. Nikcevic, G. Weingart