I would like to create a look for my model that is similar to the material of models in Blender "object"/"sculpt" mode. I have tried using Glossy and Diffuse nodes to make "plastic" and "rubber" (according to online tutorials) but it ends up looking wrong; I want it to have a sort of rubber-putty 'sheen' rather than a plastic 'shine', if that makes any sense. I am new to this, so there may be something obvious that I am missing. Perhaps it is a matter of proper lighting, I am not sure. Thank you for help!
Try using a Diffuse BDSF node (in cycles, of course), and play with the 'roughness' setting'. If your rig is like mine (not very powerful), it may be helpful to put your 3DView in render mode, hide everything except for maybe a cube or small icosphere (set to shade smooth), and then apply this diffuse material. Start fiddling with the roughness setting and watch as the render appears. You might find you'll get something that works.
Also, keep in mind that the 3DView in object mode uses 2 or 3 openGL lights of various colors and at difference positions in relation to the 3d View camera (not the render camera). Go to File > User Preferences > System tab and look at the upper right where you should see these "Solid OpenGL Lights" definitions. You can use this to help you decide how set up your scene lighting which should render the way you want.