Hi Ava,
I don't know of any built-in functionality in Matlab to do this, but there is a set of functions called "Nurbs Toolbox" on the File Exchange that could help with generating the model (<http://www.mathworks.com/matlabcentral/fileexchange/26390-nurbs-toolbox-by-d-m-spink>). You can then manipulate the control points of those surfaces.