1. A method of controlling an engineering design software application with a user interface comprising a touchscreen providing input to the engineering design software application and an overlay removably fittable onto the touchscreen, wherein the touchscreen comprises a plurality of spatially distinct points and is operable to display a plurality of engineering design elements, the method comprising the steps of: (a) identifying among the plurality of engineering design elements a first desired engineering design element to be input to an engineering design and displaying the first desired engineering design element on the touchscreen; (b) locating a first tactile representation corresponding to the first desired engineering design element, wherein the first tactile representation is removable from and repositionable upon the touchscreen; (c) placing the first tactile representation onto the overlay at a position above a first location where the first engineering design element is displayed on the touchscreen; (d) identifying among the plurality of engineering design elements a second desired engineering design element to be input to the engineering design and displaying the second desired engineering design element on the touchscreen; (e) locating a second tactile representation corresponding to the second desired engineering design element, wherein the second tactile representation is removable from and repositionable upon the touchscreen; (f) placing the second tactile representation onto the overlay at a position above a second location where the second engineering design element is displayed on the touchscreen; (g) identifying by touch and responsive non-visual cue an engineering design element output point on the first tactile representation; (h) identifying by touch and responsive non-visual cue an engineering design element input point on the second tactile representation; and (i) creating an engineering design by connecting the engineering design element output point on the first tactile representation and the engineering design element input point on the second tactile representation by means of tactile input to the touchscreen and responsive non-visual cue wherein a resulting connection is visually represented on the touchscreen by a displayed line.