when they need to conceptualize for new shapes other than the basic square/circle/rectangle/triangle!.. 
sketch.
Well Unique, there are many methods of generating form. Is there a particular project that you are working on now, or is this just a general question?
No matter, I will list some ideas here and you can chime in later. One method used is what I like to call the controled accident (also called freeform). This is where one would draw or sculpt without any particular idea in mind for the final form. Then after developing some ideas stand back and analyze them. Pick out the strongest and start developing those. This is difficult to describe in text…but let me give you a more real world example of doing this. Take out a sheet of paper and a pencil/pen. Now without looking at the paper draw a continous line all over it making quite a mess. When you look at the mess you’ve created, look for interesting shapes in it, and try to draw them on another sheet and start refining it.
A more concrete method is to go and get a ton of pictures of products, architecture and graphics that have the shapes that you want. In this case, you may want to get some pics of Gehry buildings, italian motorcycles and Nike backpacks. Try drawing bits and pieces of the pictures you’ve assembled. Move on to trying to draw your concept but make it look like a mini-gugenheim. Eventually, you will find yourself moving far off away from the pictures you’ve assembled, but you will keep drawing shapes in a similar way. Don’t worry about copying. When you look at your final concept…if it looks like a copy, you need to do more work. If it doesn’t, great!
You can also do drawing exercises. Make a circle. Cut it in half, skew it, combine it with a another basic shape, squash it and so on.