Here is the link for my Grasshopper file: http://www.sendspace.com/file/b2lhhg
This is the general view of my grasshopper structure, which included different layers. The most important parameter in the whole structure is the y-size in the first layer ( indicated in green on the picture ).
By adjusting the y-size ( indicated by red arrow on the picture ), users are able to change the width of the stool easily and the holes on the stool are equally distributed on the surface automatically.
By adjusting the factor ( indicated by the red arrow on the picture ), users are able to change the length of the legs, as well as the height of the stool.