Thank You Very much.

The last line newFace = selection[1].offset(-.25) is wrong! Try selection=model.selection newFace = selection[1].offset(-0.25) OR newFace = model.selection[1].offset(-0.25) The error is actually quite clear - it is telling you that 'selection' hasn't been defined ... Note it's best to use 0.25 NOT .25 Also how do you know what selection[1] is going to be ??? The API's offset() method is to offset a point3d by a vector3d + an optional length BUT there is an offset() method that can be added for faces, edges etc - BUT this is added by another script [by Rick Wilson?], but I don't see you 'requiring' it at the start of your code... Another tip: your input... defaults = [10,20,15] fixes the inputs as integers, if you want the input in inched use decimal numbers: defaults = [10.0, 20.0, 15.0] OR defaults = [10.inch, 20.inch, 15.inch]