Abstract: A device for generation of a parametric model associated with a 3D geometry includes a converter capable of converting a specifications tree into a graphical user interface in which, for at least one active element of the tree, there is associated a dialog box including at least one field associated with at least one control parameter of the active element. The adjustment of the control parameter can be modifiable by the user with the help of a parameter editor, each adjustment of the control parameter being displayed in the corresponding field of the dialog box and automatically bringing about the change of the adjustment of the control parameter of the corresponding active element in the specifications tree.