Sheet metal developing tool for square and rectangular hoppers

As a fabricator of 40+ years, the last 30 or so as the workshop manager, I have constantly used trigonometry etc. to calculate cones, segmental bends and much more. Nowadays I am constantly asked by the fabricators to calculate developed lengths etc. to save them the time and effort of laying it out. I have developed this app so that they can do it for themselves and therefore save “MY TIME”.