Desktop app for engineering calculations

We are an engineering office and we need a reliable desktop calculator that lives on the workstation and does not depend on a browser or an internet connection. The core job is to take a set of input parameters, run them through the formulas our engineers use every day, and return results that we can trust for real design work. We want the interface to be plain and fast: fields on the left, results on the right, and no clutter that gets in the way of daily use.

Beyond the formulas themselves, the program has to carry the reference material our people constantly look up. Built-in tables for materials, coefficients and standard cross-sections should be searchable and easy to keep updated. Every calculation must be saveable as a named project file so that a colleague can reopen it later, see the exact inputs, and reproduce the answer without guessing what was entered. Version history inside a project would be a real bonus.

Finally, we need clean printed output. A calculation should produce a tidy sheet with the inputs, the formulas applied and the final figures, ready to attach to a report or hand to a client. Please describe your approach to the desktop framework, how you would structure the formula engine so we can extend it, and how you would handle the reference database and the print layout.