Clean Some 3D Printable Models and make reference renders

We need to hire in an extra hand to help us with our workload at www.printablescenery.com. We have several models that require a full quality check and fix [login to view URL] You will need a high level of 3D modeling skill for this and you will need to completely understand how models need to be prepared for 3D Printing All 40 files need checking and fixing. no modifications needed. Please make sure all the objects are manifold and hollow, no multiple shells, inverted normals, overlapping/intersecting triangles, etc. You must be be very careful and double check each one. You will need to provide render of each one with the reference file name