This type of 3-dimensional figure should not be attempted as a tactile graphic as shown in print. Instead, you may split each figure into layers and show a tactile of each layer.
I will attach a pdf file giving examples and the suggested method of reproducing cube structures. In your example, there are some cubes that have no cubes below them (that is, it is not a solid structure), so you would use the layering method. Since there are usually several of these shown throughout a series of questions in print, you can add an explanation on the transcriber's note page, rather than giving a detailed explanation each time they occur. Then for each occurance you can use a simple transcriber's note (in 7 or less words) to indicate to the reader how many layers are in the structure.
Also included is a method developed by Susan Osterhaus, which clearly illustrates cube structures that have no "missing" blocks. I've included both in the same pdf example. I think you will find these to be much more readable than using a 3-D drawing with shading.
P.S. Please note that there are 3 pages in the file!!
edited by betty.marshall on 10/19/2010