Throughout my time with StorySlab there were various clients requiring custom ROI Calculators or forms. Typically they would share an excel spreadsheet with multiple tabs, so it can be turned into a functioning and attractive feature in the sales app that can be pulled up during sales conversations.
To look at an excel spreadsheet for a calculator and not only make it look better, but also be able to deduce what values need to be represented as inputs, which are superfluous, what to group together with other values, and what should be highlighted.
This requires a level of understanding of how the tool is intended to be used, who is going to use it, and what the ultimate purpose of the calculator is.
The intended result is something that is on brand for the company its designed for and something that looks great. It is simple to use out of the box for salespeople in the middle of a sales pitch.