Calculating how many sheets of metal would be needed.

Do you already have an algorithm in mind for this problem and just need help putting it into the spreadsheet, or do you need help with algorithm development and everything? We are usually pretty good at helping people with known algorithms, but not always knowledgeable in developing algorithms.

If you need help with algorithm development, this might be a case where it is better to just find someone who has already solved it (whether using a spreadsheet or not, most solutions I find are not specifically for spreadsheets, though they may be able to use a spreadsheet as an input/output container). What I see you describing is a 2D cutting stock kind of problem. These kinds of problem are deceptively difficult, rarely having "simple" solutions. I'm not an expert in these, but my understanding is that you end up trying every possible cutting combination and then choose the best one.

If this is very early in the project, my advice would be to do a cost/benefit analysis between programming your own spreadsheet (or something in any other programming language) and obtaining a pre-programmed app that does this (might need a second cost/benefit to decide between free apps and paying for a license). Quick searches of the internet and my app store both find several pre-programmed possibilities that would likely be a lot easier than trying to program this into the spreadsheet from scratch.

Let us know how you want to proceed.