well for the simple ones all you do is: 1. make a sphere 2. duplicate it, they should be 20.48 in size each (size doesnt matter as long as they same in exact same spot. 3. shrink one to lets say 19 or 19.5 on the x y z (just slightly smaller) 4. either ignore the smaller one for now or lock it in place so you dont move it accidently 5. make another sphere and enlongate it so its a slightly flattened egg shape and place it so its partially in the first sphere 6. make the first sphere positive and enlongated one negative and group them, you should now have a cut away sphere. give it a rock material 7. unlock the 2nd slightly smaller sphere and give it a glass texture, diamond if you want it to just refract the main spheres texture or experiment. that should be it a second option on top of the above steps is to make a duplicate of the one your using for glass and apply this as a negative to the main sphere first, that gives you a hollow globe. Then repeat the above steps and the sphere looks completely different. After that you can do it to any shape. Ideally if you have a outside program like rhino3d, you can make some very odd shapes then import them in.