Yes, Mr Li has offered a spreadsheets for this and other stuff, but it is not free. Also, even after purchasing a license from him, it is not exactly open source. I believe our profession has been tunnel focused on profit for the next project. If we create open source design software it will reduce our operating costs. Open source software will not allow the novice to design without the base knowledge because it must be checked. Retail software actually allows the novice to create a product with less engineering knowledge, experience, and intelligence resulting in the euphoric scenario we are all afraid of.