Continuing Cubism

I have now completed a few more models based on space, objects/form, layering, and a diorama.  These models have definitely helped me in my understanding of Gris's cubist painting The Violin and the Glass by getting a better feeling of his composition's space by trying to develop the 2-D painting into a 3-D model.  I am having trouble really understanding the layering though and am not quite sure how I should go about determining the importance of the layers, what belongs on each layer, and why one layer should be closer to the viewer rather than another.  Some pictures of the various models are below.